Monograph
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Monograph
A monograph of the genus Polylepis (Rosaceae)
expand article infoTatiana Erika Boza Espinoza, Michael Kessler§
‡ Pontificia Universidad Católica del Perú (PUCP), Lima, Peru
§ University of Zurich, Zürich, Switzerland
Open Access

Abstract

We present a monograph of the high Andean tree genus Polylepis (Rosaceae), based on a species concept considering morphological, climatic and biogeographic distinctness as indicators of evolutionary independence. In total, we recognize 45 species of Polylepis, grouped in five sections. Polylepis sect. Sericeae is represented by 15 species in four subsections, P. sect. Reticulatae by seven species, P. sect. Subsericantes by three species, P. sect. Australes by two species and P. sect. Incanaee by three subsections with 18 species. We describe seven new species, one from Colombia (P. frontinensis), one from Ecuador (P. simpsoniae) and five from Peru (P. acomayensis, P. fjeldsaoi, P. occidentalis, P. pilosissima and P. sacra). Three species from Peru (P. albicans, P. pallidistigma and P. serrata) are re-instated as valid species. Two taxa from Bolivia (P. incanoides and P. nana) are elevated from subspecies to species rank. The morphology, habitat, distribution, ecology and conservation status of each species are documented. We also provide an identification key to the species of the genus and general introductions on taxonomic history, morphology, evolution, ecology and conservation.

Keywords

Andes, morphology, new taxa, taxonomy

Introduction

Polylepis may well be the most emblematic tree genus of the central and northern Andes. It often occurs in an otherwise treeless landscape, forming the highest forests in the Western Hemisphere at elevations of over 4800 m. Polylepis forests contain unique biodiversity and provide habitats for a wide range of Andean plants and animals. However, they also provide crucial ecosystem services for the people living in the Andes: clean water, protection against erosion, firewood, fodder and medicinal plants, amongst others. On the other hand, it has been estimated that over 90% of the natural cover by Polylepis forests has been lost over millennia of human land use, so that the majority of species are considered to be of conservation concern. For this reason, studies on the physiology, ecology and conservation of the genus Polylepis have led to the publication of hundreds of scientific papers and reports and to the establishment of numerous conservation areas and projects to safeguard the last forest remnants.

Against this background, the poor taxonomic knowledge of the genus is troublesome. Although the first monograph of the genus was already published in 1911, to date, there is still no consensus on the number of species and their delimitation, greatly hampering conservation and management of the species and forests. The reasons for the taxonomic chaos in the genus are to be found in the high phenological variability of the individual species, coupled with great similarity between species, extensive hybridization and gene flow between species, polyploidization and, possibly, even apomictic reproduction (asexual seed reproduction). Due to these reasons, standard species concepts are difficult to apply to the genus, so that different authors have taken different approaches, arriving at different species circumscriptions. The last comprehensive monograph of the genus was published in 1979 and, due to the numerous discoveries since then, there was a strong need for a modern taxonomic treatment of the genus.

In this study, we undertook this effort by combining 35 years of field and herbarium experience of the co-author, MK, with the fresh view of PhD student TB (co-author). Together, we have studied all, but three species (P. longipilosa, P. occidentalis, P. quadrijuga) of the genus in the field and have applied a novel species concept for Polylepis which is based on a combination of morphological, ecological and biogeographical distinctness. Our species concept is narrower than previous concepts and accounts for the evolutionary independence of geographically disjunct forms that were previously combined in broadly defined species. As a result, we here recognize 45 species (up from 26 in the last global count published in 2006), including seven newly-described species. We consider that this classification more accurately reflects the evolutionary variability of Polylepis than previous classifications and will provide a workable background for the conservation and management of Polylepis forests and associated biota. Naturally, every new classification must stand the test of practicability and we look forward to this in the future. Groves (2001) nicely outlined this challenge: “Taxonomy, like other fields of biology (ecology, ethology, physiology, genetics), is a dynamic science. Classifications are not engraved in stone, nor should they be; it is unfortunate that advances in the taxonomic field, unlike those in ecology and other disciplines, often require changing the names we give to species […] but that is the way it must be, and the irritation felt […] will pass quickly. Indeed, new predictions, to be tested in the field, may well emerge from the reclassification.” Only time will tell if the classification of Polylepis that we present here will, indeed, as we hope, lead to such new predictions and increase our understanding of the evolution of high Andean forests and their biodiversity.

Materials and methods

Species concepts and sectional delimitations

Bitter (1911) used a typological species concept for Polylepis in which specimens that were morphologically different to each other were assigned to different species, resulting in a treatment with 33 species. Unfortunately, Bitter had few specimens available and did not know the genus in the field. Consequently, he did not consider the intraspecific morphological variability of the species in his taxonomic study. Based on many more herbarium collections, as well as personal fieldwork, Simpson (1979) had a better idea of the natural variability of the species and used the biological species concept (Mayr 2000) which helped her to reduce the number of species recognized until that time to 15. However, some of the species recognized by her were very variable and, in a subsequent publication (Simpson 1986), she indicated that some of her species would be better treated as “species groups”, although, except for P. tarapacana and P. tomentella, she did not separate them as different species. Later, Kessler and Schmidt-Lebuhn (2006) used a phylogenetic species concept recognizing at species rank, populations with distinct morphology, biogeography and ecology, even if they show hybridization with other species. Based on this narrower delimitation of species, they increased the number of species to 26.

The species concept used here is the general lineage concept of de Queiroz (1998, 2007), in which a species is a segment of an evolutionary lineage at the population level. To separate species, we have used the species criterion of Davis and Heywood (1973) of phenetic similarity, with discontinuities that may reflect geographical, ecological or reproductive isolation. We applied this concept to morphological traits and also to biogeographical and ecological data. Biogeographically, we considered that allopatric populations of morphologically or ecologically different populations are species because they are reproductively isolated from each other and, hence, evolutionarily independent. Ecologically, we considered that morphologically- and biogeographically distinct populations that also have different climatic niches are species because they show different adaptations to the environment. While ecological data are not commonly used to define species, we consider this to be valuable information, especially since, in most cases, there are different ecological conditions within dispersal distance, showing that the ecological differences are not simply due to the different geographical ranges inhabited by the species. For instance, P. simpsoniae and P. weberbaueri, which have previously been considered to be conspecific, grow at different elevations (2500–3800 m and 3500–4970 m, respectively), yet in their distribution ranges, there are mountains that would allow them to grow at lower and higher elevations, respectively. The rather narrow species concept applied here allows us to better identify independent evolutionary entities for the conservation and management of Polylepis species and forests. We do not recognize infraspecific taxa, such as subspecies or varieties as done by Bitter (1911) and Kessler (1995a), because on present knowledge, we are unable to rank the distinctness of population. For this reason, we consider it easier to simply recognize species.

Species delimitation and identification in Polylepis relies on populations instead of single herbarium specimens, because there is phenotypical variability even within a single plant (e.g., leaf size, texture, shape and indumentum). This variability depends on the growing stage of a branch and its exposure (sun or shade). Between individuals of a species, phenotypic variability is even more pronounced depending on genetic background, as well as growing and microhabitat conditions, with individuals from sheltered and humid sites having larger leaves with more leaflets, less dense hair cover and longer inflorescences with more flowers.

We also, for the first time, provide a formal sectional and subsectional infrageneric classification of the genus to facilitate communication. This classification is based on morphological differentiation supported by climatic niches and ploidy levels. In this sectional classification, we clustered species, based on morphological similarity (number of lateral leaflet pairs, indument type of the lower leaflet surfaces, stipule sheaths and/or fruits, leaflet apex shape and fruit shape). This morphologically based separation is broadly supported by biogeography (with most species of a section or subsection replacing each other geographically), similarity in climatic niches and similarity in ploidy levels. In the two larger, more variable sections, we also applied a subsectional classification to group similar species. The orthography of sectional and subsectional names has been designated in accordance with the ‘Shenzhen Code’ (Turland et al. 2018).

The sections defined by us largely correspond to the informal groups as outlined by Simpson (1979, 1986) which are, at least, partly upheld by molecular analyses (see Taxonomic History). However, P. subsericans was placed by Simpson (1979) in her sericea group, although she mentioned that it might be shown to be in an intermediate position between the sericea group and the incana complex. Here, we place it in a separate section Subsericantes. Additionally, Simpson (1979) included P. hieronymi within the sericea group and we are placing it in section Reticulatae, based on morphological similarity with the species in this section.

Morphological analyses

Our study is based primarily on the examination of the external morphology of herbarium specimens, supplemented with observation of rehydrated material, photographs and living plants in the field. Field studies by TB were conducted in Peru (Ancash, Arequipa, Ayacucho, Cajamarca, Cerro de Pasco, Cusco, Huancavelica, Junín, Lima, Moquegua, Puno and Tacna) and Ecuador (Azuay, Chimborazo, Loja, Napo and Pichincha). MK has studied Polylepis in Venezuela (Mérida), Colombia (Antioquia), Ecuador (Azuay, Napo, Pichincha), Peru (Ancash, Arequipa, Cuzco, Lima and Puno), Bolivia (Chuquisaca, Cochabamba, La Paz, Oruro, Potosí, Tarija) and Argentina (Córdoba, Jujuy, Salta, Tucumán). Together, we have studied all, but three species of Polylepis in the field. Voucher specimens were collected according to standard herbarium techniques. Photographs of plants and associated notes were taken in the field.

All the herbarium specimens representing each species were carefully observed and those spanning the morphological variation and geographical distribution range were chosen for measurements. Characters were measured from corresponding positions on mature, reproductive plants in order to minimize variation due to developmental differences. We have chosen characters for measurements, based in part on those that have been previously used to differentiate species within the genus Polylepis (Bitter 1911; Simpson 1979; Romoleroux 1996; Kessler 1995b; Mendoza and Cano 2012). We examined more than 1400 specimens (including type material) from the Herbaria AAU, COL, CUZ, F, GOET, HUA, LOJA, MEDEL, MERF, MO, NY, QCA, US, USM, VEN and Z/ZT and the material available on Jstor (https://plants.jstor.org/) and other online Herbaria (COL, F, NY, US). The terminology used for describing the morphological characteristics of the species was based on Simpson (1979), Hickey and King (2000) and Stearn (2004).

Geographical distributions

We combined occurrence records, based on herbarium specimens with field locations and observations from previous studies from multiple sources into a comprehensive, relational database. This database comprises approximately 3,250 quality-checked records of all species of Polylepis. All coordinates were cleansed and georeferenced if needed. We created the distribution maps using QGIS 2.18.14.

Environmental data analyses

We extracted Mean Annual Precipitation (MAP) and Mean Annual Temperature (MAT) as climatic variables from the global climatic model CHELSA version 1.2 (Karger et al. 2017) working with data points from the record database (see above). We used R version 3.0.5 to analyze the climatic data applying the R packages “devtools” and “easyGgplot” to determine and visualize the climatic differences between species. To illustrate the environmental preferences of Polylepis species, we used the function boxplot. We ran ANOVAs to analyze the variance on the climatic variables among the Polylepis species to define their climatic niche differences, followed by Tukey HSD tests to determine the significant differences among the Polylepis species.

Conservation status

We based our conservation assessment on the International Union for Conservation of Nature guidelines (IUCN 2015, see <http://www.iucnredlist.org>). A full assessment following IUCN criteria gives a comprehensive evaluation of extinction risk, based on population size reduction (Criterion A), geographic range (Criterion B), population size (Criteria C and D) and qualitative estimates (Criterion E). We used the package ‘ConR’ (Dauby 2018) to estimate the geographical range parameters for a preliminary assessment of the conservation status following Criterion B. Extinction risks were assessed globally.

Taxonomic history

The genus Polylepis was described by Ruiz and Pavón (1794). The good original generic description and the large number of diagnostic features of the genus (see Morphology) meant that no generic synonyms were subsequently described. Except for Acaena ochreata by Weddell (1855), which is listed here as Polylepis ochreata, all species were correctly classified in the genus Polylepis by their describers. This accuracy of the delimitation of the genus contrasts sharply with the highly complicated taxonomic situation within the genus.

Along with the circumscription of the genus, Ruiz and Pavón (1794) described the first species, Polylepis racemosa. Subsequently, Humboldt, Bonpland and Kunth (1824) described three other species: P. incana, P. lanuginosa and P. villosa; the latter was considered synonymous with P. racemosa by Simpson (1979), as is the case here. Weddell (1855, 1857) described three other species: P. tomentella, P. sericea and Acaena ochreata, as well as two varieties within P. lanuginosa, of which var. microphylla is here recognized as an independent species (P. microphylla). Polylepis tarapacana was described by Philippi (1891). Subsequently, Hieronymus (1895, 1896), based on collections by Lehmann and Stübel, described five other species: P. besseri, P. lehmannii (= P. lanuginosa), P. pauta, P. reticulata, and P. stuebelii (= P. pauta). In 1898, O. Kuntze published the description of two new varieties within P. racemosa (tomentosa and lanata) from Bolivia, of which the latter is now treated at species level. Pilger (1906) described five additional species, based on the material collected by Weberbauer in Peru and Bolivia: P. albicans, P. hieronymi, P. multijuga, P. serrata and P. weberbaueri. Thus, at the beginning of the 20th century, 18 species of Polylepis and a few subspecies and varieties had been described.

Bitter (1911) published the first revision of Polylepis. He recognized all the species described so far, raised two subspecies and varieties to species rank and described 13 other species, nine subspecies and 18 varieties, so that he recognized a total of 33 species. Unfortunately, Bitter did not consider the variability of individual populations and adhered to a typological species concept, so that many of his taxa were based on only one herbarium specimen. The result was a completely confusing taxonomic classification of the genus. Only six species newly described or recognized by Bitter are recognized as valid here: P. australis, P. crista-galli, P. pallidistigma, P. quadrijuga, P. rugulosa and P. triacontandra. Subsequently, Bitter (1913) described another variety of P. australis, while other authors described five further Polylepis species, although only one of these is still recognized as accepted: Benoist (1934) P. subintegra (= P. ochreata), Macbride (1934) P. subsericans and Cuatrecasas (1941, 1942) P. boyacensis (= P. quadrijuga), P. cocuyensis (= P. quadrijuga) and P. quindiensis (= P. sericea).

In the first modern revision of the genus Polylepis, Simpson (1979) brought order into this chaos. She reduced the number of species to 15 broadly delimited species of which only one (P. pepei) was described as new; infraspecific taxa were not recognized. Simpson showed a tendency to expand the species and some of the species as circumscribed by her include notable variability. Accordingly, not much later, several authors separated some of Simpson’s species into different species, based on morphology and biogeography. These include the separation of P. tarapacana from P. tomentella by Simpson (1986) herself, of P. rugulosa from P. besseri by Kessler (1995c) and of P. microphylla from P. weberbaueri by Romoleroux (1996). Kessler (1995b), taking into account the variability with P. besseri and P. racemosa as defined by Simpson (1979), but not wanting to digress too far from Simpson’s (1979) treatment, recognized three subspecies within each of them. Later, all of these were raised to species level by Kessler and Schmidt-Lebuhn (2006). In addition, after Simpson’s treatment, several new species were described, including P. neglecta (Kessler 1995b), P. canoi (Mendoza 2005) and P. pacensis (Kessler and Schmidt-Lebuhn 2006), so that, in 2006, the latter authors recognized 26 species. Since then, P. rodolfovasquezii was described by Valenzuela and Villalba (2015).

Accordingly, prior to the present study, there were 88 names available in Polylepis, of which 27 were recognized as valid at species level. In our study, we consistently applied a narrow species concept (see Material and Methods), re-instating four species to species level and describing 11 species as new. Seven of these new species are described here, while four have been described in collaboration with colleagues, namely P. argentea (Boza Espinoza et al. 2019) and P. humboldtii, P. longipilosa and P. loxensis (Boza Espinoza et al. 2020a).

Infrageneric classification

In his revision of the genus, Bitter (1911), established the two sections Dendracaena and Gymnopodae. He also recognized 11 informal groups, but he never designated if he created these as subsections or series. In the classification presented by Simpson (1979, 1986), three informal and apparently natural species groups were defined, based on morphological similarity and ecological specialization rather than a phylogenetic concept. These informal groups agreed with Bitter’s sections, except that his section Gymnopodae that was split into two. All species under Bitter’s section Dencracaena were placed in the sericea group, whereas section Gymnopodae was divided into the reticulata group and the incana complex. Simpson’s informal classification has a certain level of agreement with the AFLP phylogeny presented by Schmidt-Lebuhn et al. (2006a) which provided evidence that the sericea group represents a paraphyletic grade that subtends the other two groups (reticulata group and incana group) which are each considered to be monophyletic.

The infrageneric classification adopted here includes sections partly corresponding to the three informal and meaningful groups previously defined, based on morphology and supported by climatic niches and ploidy levels. We propose the five sections Sericeae, Reticulatae, Subsericantes, Australes and Incanaee (Table 1). Section Sericeae includes species with usually sericeous lower leaflet surfaces and/or stipule sheaths, usually with many pairs of lateral leaflets and fruits with variable numbers of spines. Within this section, we recognized four subsections: Lanuginosae, Pauta, Sericeae and Pepea. Species in section Reticulatae have relatively few lateral leaflets pairs, rugose or shiny upper leaflet surfaces and emarginate leaflet apices. Section Subsericantes includes three species with characters intermediate between those of sections Sericeae and Incanaee, with only one pair of lateral leaflets, pilose or strigose hairs on the leaflets and fruits with 3–4 irregular flattened ridges with a series of spines. Section Australes includes two species with numerous, largely glabrous leaflets and very distinctive winged fruits. Finally, species in section Incanaee usually have few lateral leaflet pairs (often only one), frequently glabrous upper leaflet surfaces and fruits with variable number of flattened ridges with a series of spines. Within this section, we recognize three subsections: Racemosae, Besseria and Incanaee. We refrain from using Bitter’s (1911) sectional names because his classification differs in important aspects from ours and we consider that keeping distinct names for different classifications will avoid confusion.

Table 1.

Alignment of the species of Polylepis according to the infrageneric classifications of Bitter (1911), Simpson (1979) and the present study.

Species Bitter (1911) Simpson (1979) This study
Section Group Group Section Subsection
P. lanuginosa Dendracaena unnamed / Latifoliatae Sericeae Sericeae Lanuginosae
P. multijuga Plurijugae
P. longipilosa Pauta
P. pauta Annulatipilosae
P. serrata Plurijugae
P. albicans unnamed Sericeae
P. argentea
P. canoi
P. frontinensis
P. humboldtii
P. loxensis
P. ochreata Annulatipilosae
P. sericea
P. pepei Pepea
P. rodolfo-vasquezii
P. hieronymi Subtustomentosae Reticulatae
P. microphylla unnamed Reticulatae
P. occidentalis
P. quadrijuga Supranitidae
P. reticulata
P. simpsoniae
P. weberbaueri
P. australis unnamed* Incanaee Australes
P. neglecta Gymnopodae
P. flavipila Subsericantes
P. pilosissima
P. subsericans Sericeae / Incanaee
P. acomayensis Incanaee Incanaee Racemosae
P. incarum
P. lanata
P. pacensis
P. racemosa unnamed*
P. sacra
P. triacontandra Paucijugae
P. besseri unnamed Besseria
P. crista-galli Paucijugae
P. pallidistigma
P. rugulosa
P. subtusalbida
P. fjeldsaoi Incanaee
P. incana Paucijugae
P. incanoides
P. nana
P. tarapacana Paucijugae
P. tomentella

Morphology

Growth habit

All species of Polylepis are woody plants growing as trees, multi-stemmed trees or shrubs (Fig. 1). As a result of their peculiar branching pattern, young plants of all species display shrub-like growth in the first few years. Adult height is usually between 1 m and 20 m, but trees of up to 32 m have been measured (Hertel and Wesche 2008). Simpson (1979) claimed that P. pepei is the only species of the genus to have a purely shrub-like growth form, but we have seen single-stemmed individuals up to 3 m tall that thus fulfil the criteria of a tree (Miehe et al. 2007). On the other hand, P. microphylla, P. nana and P. rodolfovasquezii mainly also have shrub-like growth, even though occasional trees are found in P. microphylla and P. rodolfovasquezii. Many individuals of P. tarapacana also only reach shrub form at their distributional limit in arid south-western Bolivia. Generally speaking, tree height within species decreases with decreasing temperatures (at high elevations) and precipitation (Hoch and Körner 2005; Kessler et al. 2014; Camel et al. 2019a), but in arid regions, there are complex interactions, so that shady (colder but more humid) habitats have taller trees than sunny (warm) slopes (Kessler et al. 2007). In many places, excessive logging or fires destroy the apical meristem, leading to the formation of numerous new shoots and thus to shrub-like growth. The trunk and branches usually have a gnarled, often twisted habit; occasionally the trunk lies on the ground for several meters (Young 1993). The trunk can be over 1 m thick (Koepcke 1961; Young 1993; Hertel and Wesche 2008) but is usually much slimmer.

Figure 1. 

Growth habit of Polylepis species: tree growth form: A P. microphylla, Chimborazo, Ecuador B P. fjeldsaoi, Lucanas, Peru C P. rugulosa, Moquegua, Perú D P. sacra, Mantanay, Cusco, Peru E P. acomayensis, Paruro, Cusco, Peru F P. pilosissima, Lima, Perú G P. simpsoniae, Cajas, Azuay, Ecuador; shrubby growth form H P. pallidistigma, Azángaro, Puno, Peru I P. tarapacana, Santa Rosa, Puno, Peru J P. microphylla, Chacan, Cusco, Peru. Photographs A E. Bastidas B, C, E E.G. Urquiaga F D, F–I T.E. Boza E.

Bark

The bark of Polylepis is one of the characteristic features of the genus. Indeed, the name Polylepis is derived from the Greek words poly (many) and lepis (layers, skins), referring to the shredding, multilayered bark that is common to all species of the genus. The bark can be made up of more than 100 such layers (Miyagawa 1975; Kessler 1995a) and may be up to 3 cm thick, but is usually no thicker than 1 cm (Kessler 1995a). Within the genus, there are differences in the thickness, structure and color of the bark. In section Sericeae, species. such as P. pepei, P. rodolfovasquezii and P. sericea, have a bark that is thin, flakes off in relatively thick, long stripes and, when fresh, has a light brown to orange-brown color (Fig. 2). The bark of members of section Reticulatae, such as P. hieronymi, has a similar structure, but a more grey-brown color (Kessler 1995a). In species of sections Australes, Incanaee and Subsericantes, the bark typically is significantly thicker, flakes off in thin, short pieces and has a deep red-brown color. Despite these general trends, because the bark characteristics also change with tree size and environmental conditions (wind, cover of epiphytes, etc.), there is much variation in bark development between individuals of the same species and bark characters are not of taxonomic value at the species level.

Figure 2. 

The multi-layered, shredding bark characteristic of all species of the genus A P. multijuga Cajamarca, Peru B P. hieronymi cultivated at Zurich Botanical Garden C P. humboldtii Chimborazo, Ecuador D P. pepei La Paz, Bolivia E P. incana Papallacta, Ecuador F P. pauta Ecuador G P. sericea Colombia H P. canoi Junin, Peru. Photographs A, E E.G. Urquiaga F. B, C, F T.E. Boza E. D A. Fuentes G A. Möhl H H.R. Quispe.

Branching pattern

The branching of Polylepis is sympodial (Bitter 1911; Simpson 1979, 1986; Kessler 1995a). Polylepis trees tend to have twisted stems and branches which might be related to the windy, cold and arid habitats (Simpson 1979). The branches often show a striking arrangement of the leaves: on young shoots, the leaves are usually all closely clustered at the top, causing a shrub-like growth, whereas the basal internodes stretch rather significantly afterwards, typically for 5–12 cm (Bitter 1911; Simpson 1979; Kessler 1995a) (Fig. 3). This branching mode is a typical feature of the genus but appears not to be useful to distinguish species. Only the degree of compression of the end rosette varies between species, with species of section Sericeae having less compressed shoots (Bitter 1911). However, this character is difficult to quantify, since its expression can vary greatly depending on the location and age between individuals of a species and even on a plant, for example, on shade and sun shoots (Kessler 1995a). In Polylepis, the petioles usually remain on the branches for a long time even after the leaves have fallen off.

Figure 3. 

Branching patterns of Polylepis: petioles remaining on the branches A P. rugulosa Moquegua, Peru F P. incana Napo, Ecuador; leaves closely clustered at the top of the branches B P. pallidistigma Puno, Peru E P. rodolfo-vasquezii Huancavelica, Peru; twisted stems and branches C P. humboldtii Chimborazo, Ecuador D P. sacra Cusco, Peru. Photographs A–D T.E. Boza E. E G. Vargas F E.G. Urquiaga F.

Stipule sheaths

Another characteristic feature of the genus is the growth of the two stipules fused around the branch, forming a sheath. The sheaths are congested at the ends of the shoots and shaped like tubes nested inside each other (Fig. 4). These remain intact for several years even after the leaves have fallen off and provide some taxonomically important features: a) Small spurs can be found on both sides of the petiole at the upper margin. Their size, shape and hairiness are relatively constant within the species; b) The hair type on the outside of the stipule sheaths also varies significantly between the species; c) Long, coarse or woolly hair often extends from the inside of the stipule sheaths beyond the edge of the sheaths. With increasing age, the stipule sheaths become bald; an examination of young shoots is therefore necessary (Simpson 1979; Kessler 1995a). However, short glandular hairs are often easier to find on older stipule sheaths than on young sheaths, since they are then no longer covered by longer wool or felt hairs.

Figure 4. 

Stipule sheaths congested at the ends of the shoots A P. multijuga Cajamarca, Peru B P. reticulata Azuay, Ecuador C P. ochreata Pichincha, Ecuador D, E P. fjeldsaoi Ayacucho, Peru F P. weberbaueri Ancash, Peru G P. subsericans Cusco, Peru. Photographs A, D–F E.G. Urquiaga F. B, C, G T.E. Boza E.

Indument

The types and density of hairs represent some of the most important taxonomic features within the genus, although there are significant fluctuations especially in the length and density of the hair within species (Fig. 5). Hairs can be found on the stipule sheaths, petioles and rachises, under- and uppersides of the leaflets, flower bracts, sepals, stamens, styles and fruits, often with different hairs on different organs.

Figure 5. 

Lower leaflet surfaces of Polylepis species with different types of hairs. Lanate: A P. lanata B P. serrata. Pannose: C P. besseri D P. rugulosa. Sericeous: E P. rodolfo-vasquezii F P. sericea. Tomentose: G P. microphylla H P. reticulata. Pilose: I P. flavipila J P. pilosissima. Villous: K P. acomayensis. Puberulous: L P. neglecta. Strigose: M P. subericans. Photographs by T. E. Boza E.

Bitter (1911) distinguished two groups of hairs: multicellular, mostly glandular capilli resiniferi or capilli pulverulenti and unicellular, non-glandular hairs as pili. Since there is a great variability in this last group in particular (Simpson 1979; Kessler 1995a; Romoleroux 1996), we here recognized eight hair types, with the terms following Hickey and King (2000).

  1. Lanate: woolly, long, interwoven hair that gives a rough, woolly impression.
  2. Pannose: felt-like, composed of densely matted woolly hairs.
  3. Pilose: softly hairy, with short hairs.
  4. Puberulous: slightly hairy (minutely pubescent).
  5. Sericeous: silky, short to long, straight, smooth-fitting hair that give a silky impression.
  6. Strigose: long, straight, rough or stiff hairs or bristles that give a rough-haired impression.
  7. Tomentose: densely covered in soft and very curled hairs.
  8. Villous: covered with long, shaggy hairs.

In some species, glandular hairs are intermixed with the longer hairs, often tinting the latter ones yellowish, as in P. flavipila and P. incana. In other species, only glandular hairs are found on some organs. In the extreme case of P. tarapacana, the resin forms a thick, translucent layer on the upperside of the leaflets.

Leaves and leaflets

The imparipinnate leaves provide some of the most important taxonomic features within the genus, especially since their features are often correlated with those of the inflorescences and fruits. In addition, they can be determined, based on vegetative material. Important features are:

Figure 6. 

Leaflet sizes in Polylepis: A P. microphylla; 0.3–0.7 × 0.2–0.5 cm B P. rodolfo-vasquezii; 0.9–1.1 × 0.4–0.6 cm C P. tarapacana; 0.7–0.8 × 0.3–0.4 cm D Polylepis fjeldsaoi; 1.2–2.1 × 0.6–0.7 cm E P. incana; (1.4–)1.8–2.7 × 0.4–0.7 cm F P. subsericans; (1.3–)1.7–2.8 × 0.5–0.7 cm G P. canoi; (2.4–)3.4–3.9 × (0.8–)1.1–1.5 cm H P. humboldtii;1.8–2.8 × 0.6–0.9 cm I P. multijuga; 2.9–3.6(–5.4) × 1.1–2.0 cm. Photographs A, D, E, I E.G. Urquiaga F. B G. Vargas F T.E. Boza E. G H. Huaylla H E. Bastidas.

  1. Number of lateral leaflets pairs, which can range from 1 to 7 (Fig. 6), but often varies within the species and even on one specimen, for example, on sun and shade branches. Plants growing under more humid conditions tend to have more leaflets, so that even species which normally only have a single pair of lateral leaflets (e.g., P. tomentella) can have a second pair of smaller ones (Kessler 1995a, b).
  2. Leaflets size (Fig. 7). For the largest pair of leaflets in a leaf, this ranges from about 0.3–0.7 × 0.2–0.5 cm in P. microphylla to 2.9–3.6(–5.4) × 1.1–2.0 cm in P. multijuga.
  3. Leaflet shape (Fig. 8), which can range from elliptic to ovate and obovate.
  4. Leaflet apex (Fig. 8), which can range from acute to deeply emarginate.
  5. Leaflet margin (Fig. 8), which can range from entire to serrate.
  6. Number of teeth/crenations in non-entire leaflets.
  7. Upper leaflet surface hair type, density and length.
  8. Lower leaflet surface hair type, density and length (Fig. 5).

Inflorescences and flowers

The inflorescences are simple clusters, rarely branched, generally long and pendulous as in P. multijuga (15.4–36.0 cm; 47–83 flowers), P. ochreata (8.1–17.4 cm; 21–49 flowers) and P. serrata (7.6–17.3 cm; 16–35 flowers). In other species, the inflorescences are more reduced, in the extreme to the axillary region of the leaves, such as in P. microphylla (3.8–5.3 cm; 1–3 flowers), P. pepei (1.2–3.5 cm; 3 flowers) and P. rodolfovasquezii (0.9–1.1 cm; 1 flower) (Fig. 9).

Figure 7. 

Number of lateral leaflets pairs in Polylepis: A P. subsericans (1) B P. serrata (4–7) C P. weberbaueri (2–3) D P. microphylla (3–6). Photographs by T. E. Boza E.

Figure 8. 

Leaves showing leaflet shapes, margins and apices in the sections and subsections of Polylepis: section Sericeae: A P. multijuga; elliptic, serrate, obtuse (subsect. Lanuginosae) B P. ochreata; elliptic, entire to slightly serrate, emarginate (subsect. Sericeae) C P. pauta, elliptic, crenate, emarginate (subsect. Pauta) D P. rodolfo-vaquezii, elliptic, entire, emarginate (subsect. Pepea). Section Reticulatae: E P. microphylla, broadly elliptic, entire, deeply emarginate F P. reticulata, elliptic to obovate, entire or slightly crenate, deeply emarginate. Section Australes: G P. australis, elliptic, serrate, emarginate. Section Incanaee: H P. besseri, obovate, crenate, obtuse or emarginate and I P. pallidistigma, elliptic, crenate, round or emarginate (subsect. Besseria) J P. tarapacana, obovate, entire or very slightly crenate, obtuse or acute and K P. incana, elliptic to obovate, crenate, obtuse to emarginate (subsect. Incanaee) L P. acomayensis, narrowly obovate, crenate, round to emarginate and M P. sacra, obovate, crenate, emarginate (subsect. Racemosae) N P. flavipila, obovate, crenate, acute or emarginate. Section Subsericantes: O P. subsericans, narrowly elliptic, entire to slightly serrate, round or emarginate. Photographs A, E, K, L E.G. Urquiaga F. B–G, M, O T.E. Boza E. H M. Kessler J A. Domic D G. Vargas.

Figure 9. 

Inflorescence length and number of flowers in Polylepis: A P. multijuga (15.4–36.0 cm; 47–83) B P. pepei (1.2–3.5 cm; 3) C P. subsericans (1.9–5.6 cm; 3–6) D P. rodolfo-vasquezii (0.9–1.1 cm; 1). Photographs A E. G. Urquiaga F. B A. Fuentes C, D T.E. Boza E.

The flowers of Polylepis are hermaphroditic and have a number of adaptations to wind pollination: the petals are missing, the 3–4 sepals are mostly green or rarely red, nectar or fragrances are missing, the stamens are exerted and the styles are multilobed. Previous taxonomic work has rarely taken into account flower features. However, Simpson (1979) previously pointed out that the number of stamens differs among and within the species (Fig. 10). Indeed, we have found great variability, fluctuating from P. pepei (5–9 stamens per flower) to P. sacra (23–27) and we use this trait for species delimitation. The anthers have long purple filaments, are always hairy, and colored red or violet, apparently without taxonomically informative variation (Bitter 1911; Simpson 1979; Kessler 1995a). In contrast, the length of the styles differs between species and is here used for the first time to differentiate species in Polylepis. Style length ranges from 0.9–2.0 mm in P. australis to 3.0–4.9 mm in P. pepei.

Figure 10. 

Number of stamens in Polylepis A P. albicans (7–18) B P. rodolfo-vasquezii (13–15) C P. sacra (23–27). Photographs A, C T.E. Boza E. B G. Vargas.

Fruits

The fruits are indehiscent achenes that envelop the single carpel with only one ovule. The surface has differently-shaped protuberances including irregular flattened ridges (as in section Subsericantes), flattened spines (in sections Sericeae and Reticulatae), thick wings and ridges (in sections Incanaee and Subsericantes) (Fig. 11) and thin wings (in section Australes). These traits are thus useful for sectional and subsectional delimitation, but, with a single exception (P. crista-galli), do not have taxonomic value for species delimitation. On the other hand, the extent and type of hair on the fruits are of taxonomic value at species level. The seeds are elongated, spindle-shaped, with a thin or subcoriaceous testa (Romoleroux 1996).

Figure 11. 

Fruit type in Polylepis: A P. reticulata: variable numbers and placement of flattened spines B P. pauta: with variable numbers and placement of flattened spines C P. flavipila: irregular flattened ridges with a series of spines D P. subsericans: irregular flattened ridges with a series of spines E, F P. australis: 2–3 irregular and pronounced thin wings. Photographs by T. E. Boza E.

Evolution

The evolutionary history of Polylepis is poorly understood. This is linked to the complex taxonomy of the genus, which has led to highly variable classifications over time (see Taxonomic history) and which, in itself, is due to the recent and presumably ongoing radiation of the genus coupled with hybridization and polyploidization. We here review these aspects with respect to their relevance for the taxonomic treatment of the genus.

Pollination biology and seed dispersal

Polylepis is wind pollinated. Earlier studies suggested low dispersal distances in the range of a few tens of meters (Salgado-Laboriau 1979; Salgado-Laboriau et al. 1984; Kessler 1995a). However, pollen dispersal of up to 80 km was later documented in P. australis (Seltmann et al. 2009a) and genetic studies also document extensive gene flow between populations (Schmidt-Lebuhn et al. 2006b; Seltmann et al. 2009a), suggesting extensive long-distance pollen dispersal. Likely, as is typical for wind-dispersed plants (Whitehead 1983; Friedman and Barrett 2009), most pollen is dispersed over short distances, while there is also substantial long-distance pollen dispersal. Selfing can occur in Polylepis, although in P. australis, seed germination rates are lower in selfing than in outcrossed pollination, presumably due to incomplete gametophytic self-incompatibility (Seltmann et al. 2009b).

The fruits of Polylepis are poorly adapted for long-distance dispersal. Some species have long thin spines that appear to be adapted for ectozoochoric dispersal, whereas others have thin wings designed for wind dispersal (Simpson 1979, 1986). Nevertheless, actual fruit dispersal distances appear to be in the range of tens of meters (Enrico et al. 2004; Torres et al. 2008; Quinteros-Casaverde et al. 2012). Dispersal of Polylepis fruits over distances of hundreds of meters to a few kilometers may only occasionally occur in the fur of animals or in mud on the animal’s feet. Accordingly, gene flow in Polylepis is likely to be mainly due to pollen dispersal (Schmidt-Lebuhn et al. 2007).

A further potential unknown complication in Polylepis may be the occurrence of apomixis (asexual seed production). Apomixis leads to taxonomic complications because the scarcity of sexual reproduction leads to the formation of numerous clonal lineages that are evolutionarily partly independent (Campbell and Dickinson 1990; Richards et al. 1996). Apomixis is well known in taxonomically complex genera of Rosaceae such as Alchemilla, Crataegus, Rubus and Sorbus (Nybom 1988; Talent and Dickinson 2007; Gehrke et al. 2008; Pellicer et al. 2012; Samaniego et al. 2018). Kerr (2004) suggested that apomixis might occur in Polylepis, but so far, this has not been confirmed.

Hybridization

Hybridization is widespread in the plant kingdom and is also well known in Rosaceae (Dickinson et al. 2007; Lo et al. 2009; Robertson et al. 2010). Hybridization includes a wide range of phenomena, ranging from occasional hybridization events between evolutionarily independent species where the offspring does not further reproduce, to hybridogenic species formation (Mallet 2007; Rieseberg and Willis 2007; Whitney et al. 2010). Polylepis is no exception in this regard, although this was long overlooked due to the similarity of the species and, accordingly, the difficulty of identifying hybrids.

Simpson (1979, 1986) was the first to suggest hybridization between species of Polylepis, based on morphologically intermediate specimens between P. incana and P. racemosa. Later, based on her morphological taxonomic revision of the Ecuadorean species, Romoleroux (1996) proposed that the following species hybridize where their ranges meet or overlap: P. incana and P. pauta, P. incana and P. ochreata (as P. sericea), P. incana and P. reticulata and P. pauta and P. ochreata (as P. sericea). These hybrids are also recognized in the present treatment.

For Bolivia, also based on morphological intermediacy in mixed species forests, Kessler (1995a, b) identified further putative hybrid individuals and populations. These ranged from occasional individuals found where two species meet, to large hybrid zones up to hundreds of kilometers wide, although some of these are now interpreted differently. Kessler (1995a, b) reported occasional hybrids between P. besseri and P. incanoides, P. besseri and P. tomentella, P. incanoides and P. subtusalbida, P. incarum and P. triacontandra and P. neglecta and P. subtusalbida. All of these are also recognized here. More extensive hybridization was found in an extensive introgression zone at the locality Mojón, Cochabamba, where P. besseri, P. lanata and P. subtusalbida meet and form a large hybrid swarm in which all possible combinations of character traits among the three species can be found in an area of a few square kilometers. At an even larger scale, in southern Bolivia, there is a large region about 200 km wide where P. tarapacana and P. tomentella broadly intergrade. Simpson (1979) used this intergradation to justify treating both as conspecific, but later considered that the species are sufficiently distinct over most of their respective ranges to be treated as distinct species (Simpson 1986). Kessler (1995a, b) followed suit and treated the intermediate populations as a hybridization zone. A further putative intermediate population was recognized by Kessler (1995a, b) between P. lanata and P. triacontandra. However, this population was later studied in more detail and is now recognized as the distinct species P. pacensis (Kessler and Schmidt-Lebuhn 2006).

Besides these hybridization events between extant taxa, there is also indirect evidence for speciation via hybridization. Schmidt-Lebuhn et al. (2006a) proposed that P. crista-galli may have originated from hybridization between an ancestor of P. australis/neglecta and P. subtusalbida. This is based on the fact that, in the small area of geographical overlap between P. neglecta and P. subtusalbida, Kessler (1995a, b) found two hybrid individuals with intermediate characters between the parent species and that are morphologically indistinguishable from P. crista-galli. Genetically, P. crista-galli also appears to be intermediate between the putative parental species (Schmidt-Lebuhn et al. 2006a). Interestingly, the current range of P. crista-galli in southern Bolivia to northernmost Argentina almost perfectly fills the distributional gap between P. neglecta (central Bolivia) and P. australis (Argentina). This suggests that an ancestral form of P. australis/neglecta might have occurred from central Bolivia to Argentina and that the central part of this range was lost due to hybridization with P. subtusalbida or a related species, resulting in the formation of P. crista-galli. Based on morphological intermediacy, in the present study, we also propose further candidates for hybridogenic speciation, such as P. albicans or P. frontinensis, in both cases involving a member of section Sericeae and a member of section Reticulatae. Other species of potential hybridogenic origin include P. incarum and P. racemosa.

Summarizing, based on morphological traits, hybridization in Polylepis appears to be common, ranging from cases where species occur sympatrically, but where no putative hybrids have yet been found (Kessler 1995a) to cases of occasional primary hybridization between two well characterized species, large hybrid swarms between two or three species and, finally, even cases of hybridogenic speciation that may have wiped out part or all of the parent species. Interestingly, the majority of hybridization events known in Polylepis are between species of different sections or subsections. This may partly be because species of a section or subsection are mostly allopatric, so that they cannot easily hybridize, but also because it might be difficult to recognize hybrids between species that are morphologically very similar, as is typical within sections or subsections.

Direct molecular evidence of hybridization in Polylepis is still lacking. However, both Kerr (2004) and Schmidt-Lebuhn et al. (2006a), using molecular markers, found low levels of phylogenetic resolution, based on AFLP (amplified fragment length polymorphism) and sequence data, respectively and that geographically separate accessions of widespread species tend to cluster genetically with geographically close individuals of unrelated species rather than with their conspecific samples from geographically more distant locations. Based on incongruence between chloroplast and nuclear markers, Kerr (2004) even found evidence of hybridization between Polylepis and the closely related genus Acaena. All this suggests that gene flow between species of Polylepis may be even more frequent than inferred from morphology alone.

Ploidy levels

Changes in ploidy level are an important macro- and microevolutionary processes (Adams and Wendel 2005; Jiao et al. 2011). Polyploidy results from either auto- or allopolyploidization, the latter often linked to hybridization, where it allows for the stabilization of genomes of mixed origin (de Wet 1971; Tate et al. 2005). Besides its evolutionary implications (Weiss-Schneeweiss et al. 2013), polyploidy is also of taxonomic relevance, since populations of different ploidy levels are at least partly reproductively isolated, allowing for divergent evolutionary trajectories that can be treated at species level (Soltis et al. 2007). Rosaceae is renowned for the occurrence of polyploid complexes, for example, in Crataegus (Lo et al. 2010) and Sorbus (Robertson et al. 2010; Pellicer et al. 2012).

The following account of ploidy levels in Polylepis is based on Boza Espinoza et al. (2020b). Ploidy levels in Polylepis have been studied by direct chromosome counts, nucleus size measurements via flow cytometry and guard cell measurements (Table 2). Each of these methods has its own advantages and limitations. Direct chromosome counts are difficult in Polylepis due to the small size of the chromosomes and high chromosome numbers and because they require live plant material (Simpson 1979; Kessler 1995b; Quija-Lamina et al. 2010; Schmidt-Lebuhn et al. 2010). Genome size measurements via flow cytometry also require live material and do not provide direct numbers of chromosomes. Guard cell size is well known to be correlated to ploidy level in angiosperms in general (Masterson 1994; Sugimoto-Shirasu and Roberts 2003; Beaulieu et al. 2008) and Rosaceae in particular (Joly and Bruneau 2007) and has been shown to be correlated to genome size in Polylepis (Schmidt-Lebuhn et al. 2010). Still, there is notable variation of guard cell sizes within species, even when only a single ploidy level is known in the species (Schmidt-Lebuhn et al. 2010; Boza Espinoza et al. 2020b). This variation may be due to anatomical plasticity of a species depending on growth conditions, differences in measurement methods or aneuploidy. Thus, guard cell measurements allow inference of major ploidy levels, but not of minor variations in chromosome numbers or genome sizes. Such variations have been found in detailed studies of Ecuadorean species, based on genome measurements and chromosome counts (Quija-Lamina et al. 2010; Quijia Lamiña et al. 2010; Montalvo 2013; Zurita et al. 2013; Segovia-Salcedo 2014; Segovia-Salcedo and Quijia-Lamiña 2014; Caiza et al. 2018). Based on values of dozens of individuals of each species, these studies documented that many species have variable chromosome numbers and genome sizes, suggesting reductions in chromosome numbers that could be the result of aneuploidy (loss of DNA and reduction of chromosome size) and dysploidy (chromosome fusion) (Stebbins 1971; Morgan et al. 1994; Mishima et al. 2002).

Table 2.

Overview of the available data on genome sizes, chromosome numbers and guard cell sizes in species of Polylepis. Where possible, literature records were assigned to this taxonomy, but a few data points (especially from the hybrid zone at Mojanda, Ecuador) had to be excluded because they could not be unambiguously assigned to a species. Depending on data source, we report the mean ± standard deviation, only the mean or a range. Data sources: 1. Kessler (1995b); 2. Quijia Lamiña et al. (2010); 3. Montalvo (2013); 4. Zurita et al. (2013); 5. Segovia-Salcedo and Quijia-Lamiña 2014; 6. Segovia-Salcedo (2014); 7. Kessler et al. (2014); 8. Caiza et al. (2018); 9. Boza et al. (2020). Abbreviations: Ar = Argentina, Ec = Ecuador, cult. = cultivated (in botanical garden), ind. = individuals, pl = planted.

Species Genome size Chromosome number Guard cell length Inferred ploidy levels (2n = /x =)
Voucher/locality Size (pg) Voucher/locality N Voucher/locality Length (µm)
Section Sericeae
Subsection Lanuginosae
P. lanuginosa 3 ind. Sangay, Ec 6 1.42 ± 0.13 diploid / x = 6
6 ind. Zhud, Ec 2 38–42
Laegaard 55036 1 10.8 ± 1.4
Laegaard 102637 1 11.8 ± 1.6
P. multijuga Boza 3070 9 11.0 ± 2.0 diploid / x = 6
Boza 3074 9 11.2 ± 1.7
Boza 3076 9 12.8 ± 2.3
Subsection Pauta
P. longipilosa Jaramillo 10862 9 10.3 ± 1.6 diploid / x = 6
P. pauta 2 ind. Oyacachi, Ec 6 3.21 ± 0.04 tetraploid / x = 12 plus aneuploids; perhaps also diploid / x = 6
2 ind. Oyacachi, Ec 6 3.37 ± 0.18
25 ind. Papallacta, Ec 2, 5 67–83
16 ind. Papallacta, Ec 6 72
15 ind. Cayambe-Coca, Ec. 3 68–77
Kessler 2749 1 12.5 ± 1.8
Laegaard 102327 1 16.5 ± 2.8
P. pauta Oyacachi, Ec 8 14.4 ± 2.5
Papallacta, Ec 8 12.3 ± 1.9
Papallacta, Ec 9 12.7 ± 1.9
Papallacta, Ec 9 12.7 ± 2.1
Papallacta, Ec 9 16.6 ± 1.6
P. serrata Cult. Göttingen 1 1.57 ± 0.11 Cult. Göttingen 1 10.6 ± 0.9 diploid / x = 6
Cult. Göttingen 1 1.61 ± 0.11 Cult. Göttingen 1 12.7 ± 1.8
Subsection Sericeae
P. albicans Boza 3014 9 10.8 ± 1.3 diploid / x = 6
Frimer 44 9 13.5 ± 1.4
Renvoize 5074 9 12.2 ± 1.2
P. argentea Cult. Göttingen 1 1.63 ± 0.15 Cult. Göttingen 1 12.4 ± 2.4 diploid / x = 6
Cult. Göttingen 1 1.67 ± 0.15 Cult. Göttingen 1 13.0 ± 1.7
Cult. Zurich 9 13.9 ± 1.7
Chevarria 1035 9 13.4 ± 1.2
Hanold 85 9 13.4 ± 1.2
P. canoi Kessler 2880 1 14.3 ± 2.6 diploid / x = 6
P. frontinensis Kessler 2772 9 11.5 ± 1.3 diploid / x = 6
Kessler 2776 9 13.0 ± 1.3
P. humboldtii Carate 185 9 12.4 ± 1.4 diploid / x = 6
P. loxensis 25 ind. Fierro Urco, Ec 2, 5 39–42
Laegaard 19109 9 12.0 ± 1.5
Lewis 3804 9 11.4 ± 1.1
P. ochreata 2 ind. Yanacocha, Ec 6 3.41 ± 0.09 diploid / x = 6, tetraploid / x = 12, and hexaploid / x = 18; perhaps plus aneuploids or hybrids
2 ind. El Ángel, Ec 6 4.66 ± 0.57
8 ind. El Ángel, Ec 2, 5 37–40
9 ind. Yanacocha, Ec 2, 5 59–77
16 ind. Yanacocha, Ec 6 82
15 ind. Yanacocha, Ec 3 73–88
Molau 2536 9 10.7 ± 1.3
Laegaard 54474 9 11.9 ± 1.1
Romoleroux 1060 9 11.7 ± 1.0
Yanacocha, Ec 8 14.1 ± 2.3
P. sericea Dorr 5220 9 13.3 ± 1.8 diploid / x = 6
Subsection Pepea
P. pepei Kessler 2795 1 10.9 ± 1.6 diploid / x = 6
Kessler 3386 1 11.8 ± 1.6
P. rodolfo-vasquezii Cult. Göttingen 1 1.60 ± 0.07 Cult. Göttingen 1 10.2 ± 1.5 diploid / x = 6
Cult. Göttingen 1 1.70 ± 0.05 Cult. Göttingen 1 10.8 ± 1.3
Section Reticulatae
P. hieronymi Cult. Göttingen 1 1.52 ± 0.02 Cult. Göttingen 1 12.6 ± 1.8 diploid / x = 6
Cult. Göttingen 1 1.49 ± 0.04 Cult. Göttingen 1 11.9 ± 2.0
52 ind. Ar 7 1.45–1.57
Beck 9345 1 13.2 ± 1.8
Kessler 3123 1 11.2 ± 1.0
P. microphylla Cult. Göttingen 1 1.53 ± 0.06 Cult. Göttingen 1 13.9 ± 1.1 diploid / x = 6 and tetraploid / x = 12 plus aneuploids
Cult. Göttingen 1 1.53 ± 0.07 Cult. Göttingen 1 14.3 ± 2.2
2 ind. Ozongoche, Ec 6 2.03 ± 0.22
8 ind. Achupallas, Ec 2, 6 70–82
Galiano 1999 1 14.2 ± 1.8
Achupallas, Ec 8 10.7 ± 1.9
P. occidentalis Diaz 2879 9 11.3 ± 1.2 diploid / x = 6
Diaz 4012 9 10.8 ± 1.0
Sánchez 10285 9 12.7 ± 1.6
P. quadrijuga Gradstein s.n 1 12.2 ± 1.7 diploid / x = 6
Gradstein s.n 1 12.3 ± 2.0
Olivares 570 9 14.3 ± 1.3
P. reticulata 11 ind. Soldados, Ec 2 36–42 diploid / x = 6 plus higher ploidy (hexaploid / x = 18?; in cultivated plants only?)
3 ind. Oyacachi, Ec (pl) 6 ~118
Kessler 2746a 1 12.2 ± 1.4
Laegaard 102691 1 10.0 ± 0.9
Cajas, Ec 9 10.5 ± 1.8
Cajas, Ec 9 12.3 ± 1.6
Cajas, Ec 9 11.4 ± 1.4
P. simpsoniae 3 ind. Sangay, Ec 6 1.40 ± 0.08 diploid / x = 6
25 ind. Zhud, Ec 2 37–42
2 ind. Sangay, Ec 6 38
Laegaard 102677 1 12.2 ± 1.0
Cajas, Ec 9 9.1 ± 1.1
P. weberbaueri Acleto 364 1 12.3 ± 0.9 diploid / x = 6
Boza 3018 9 14.1 ± 1.1
Boza 3148 9 14.3 ± 1.5
Smith 9568 9 14.9 ± 1.1
Section Australes
P. australis Cult. Göttingen 1 2.98 ± 0.06 Cult. Göttingen 1 16.7 ± 2.6 tetraploid / x = 12 and diploid / x = 6 plus triploid/ x = 9 hybrids and hexaploid / x = 18 autopolyploid derivate
Cult. Göttingen 1 3.03 ± 0.03 Cult. Göttingen 1 17.4 ± 1.6
261 indiv. 7 2.84–2.97
75 indiv. 7 1.44–1.54
24 indiv. 7 2.09–2.24
1 indiv. 7 4.15
Kessler 3350 1 18.9 ± 1.9
Lazaro 6695 9 17.6 ± 2.4
Lorentz 760 1 12.8 ± 1.4
Venturi 3010 9 12.2 ± 1.8
w/colector 2330 9 15.5 ± 2.5
Cult. Zurich 9 22.7 ± 2.7
P. neglecta Cult. Göttingen 1 1.54 ± 0.06 Cult. Göttingen 1 ~80 Cult. Göttingen 1 13.9 ± 1.1 diploid / x = 6; perhaps also tetraploid / x = 12
Cult. Göttingen 1 1.55 ± 0.09 Cult. Göttingen 1 14.3 ± 2.2
Kessler 3531 1 13.6 ± 2.3
Kessler 3633 1 13.2 ± 2.0
Section Subsericantes
P. flavipila Boza 3163 9 17.9 ± 1.8 tetraploid / x = 12
Boza 3167 9 16.0 ± 1.5
Boza 3168 9 15.3 ± 1.6
P. pilosissima Kessler 3426 1 18.0 ± 2.0 tetraploid / x = 12
Kessler 3591 1 17.2 ± 2.2
Boza 3023 9 17.3 ± 1.6
Cerrate 1265 9 15.6 ± 1.4
Gentry 638 9 16.2 ± 1.3
Kessler 3428 9 15.7 ± 1.1
P. subsericans Cult. Göttingen 1 3.12 ± 0.18 Cult. Göttingen 1 16.6 ± 2.2 tetraploid / x = 12
Cult. Göttingen 1 3.21 ± 0.11 Cult. Göttingen 1 17.3 ± 2.2
Toivonen s.n 1 18.3 ± 1.5
Toivonen s.n 1 18.5 ± 2.4
Sylvester 428 9 13.9 ± 1.2
Sylvester 868 9 16.2 ± 1.7
Sylvester 1287 9 15.9 ± 1.8
Section Incanaee
Subsection Racemosae
P. acomayensis Boza 3135 9 16.2 ± 1.8 tetraploid / x = 12
Boza 3141 9 15.1 ± 1.4
P. incarum Jimenez 2716 1 18.3 ± 0.8 tetraploid / x = 12
Kessler 3465 1 17.2 ± 1.9
Jimenez 2716 9 17.6 ± 1.6
Kessler 13515 9 16.9 ± 2.1
Shepard 150 9 17.8 ± 2.2
P. lanata Kessler 2851 1 19.6 ± 2.1 tetraploid / x = 12
Kessler 2962 1 18.8 ± 1.7
P. pacensis Kessler 3028 1 15.9 ± 2.7 tetraploid / x = 12
Mendez & Arcienaga 14 1 17.7 ± 1.3
Kessler 14528 9 19.2 ± 1.7
Lopez & Bermejo 4 9 19.1 ± 1.9
Lopez & Bermejo 10 9 19.7 ± 2.0
P. racemosa (all pl) 2 ind. Cotopaxi, Ec. 6 4.48 ± 0.19 tetraploid / x = 12 to octoploid / x = 24, with many intermediate and aneuploid ploidy levels
2 ind. Cotopaxi, Ec. 6 2.63 ± 0.20
3 ind. Oyacachi, Ec. 6 4.57 ± 0.11
12 ind. Oyacachi, Ec 2, 5 80–82
2 ind. Oyacachi, Ec 2, 5 72–77
10 ind. Oyacaci, Ec. 6 62–80
Ferreyra 12418 1 18.0 ± 1.6
Papallacta, Ec 8 21.7 ± 3.8
Oyacachi, Ec 8 17.6 ± 2.6
Arce 161 9 17.2 ± 1.5
Arce 167 9 15.1 ± 1.3
Arce 207 9 13.8 ± 1.4
Bird 1384 9 16.1 ± 1.3
Boza 3020 9 16.7 ± 1.6
Boza 3030 9 15.1 ± 1.0
Boza 3031 9 14.2 ± 1.4
Boza 3119 9 18.0 ± 1.5
Ferreyra 3792 9 15.3 ± 1.6
Kenehira 5 9 15.9 ± 1.1
Kessler 14608 9 17.1 ± 1.1
Laegaard 20465 9 19.8 ± 2.0
Laegaard 22351 9 17.0 ± 1.9
Leiva 741 9 14.9 ± 1.2
Leiva 1090 9 16.4 ± 1.8
Nuñez 8117 9 16.3 ± 1.3
Renvoize 4847 9 17.7 ± 1.4
Sánchez Vega 5322 9 13.5 ± 1.1
Smith 11076 9 12.6 ± 1.0
Soukup 3498 9 16.7 ± 1.5
Stork 9972 9 16.6 ± 1.8
Tovar 2371 9 15.3 ± 1.4
Velásquez 12 9 16.3 ± 1.1
West 3787 9 13.2 ± 2.2
P. sacra Cult. Göttingen 1 5.76 ± 0.26 Cult. Göttingen 1 20.2 ± 3.3 octoploid / x = 24; perhaps also tetraploid / x = 12 or intermediates
Cult. Göttingen 1 5.72 ± 0.15 Cult. Göttingen 1 16.7 ± 3.3
Rosales 04 1 19.5 ± 0.8
Sylvester 644 9 15.6 ± 1.4
Sylvester 1262 9 22.1 ± 1.2
Sylvester 1270 9 15.8 ± 1.3
P. triacontandra Cult. Göttingen 1 ~80 tetraploid / x = 12; perhaps also lower ploidy levels
Beck 4976 1 18.9 ± 1.9
Kessler 3420 1 20.4 ± 1.1
Steudel 427 9 13.5 ± 1.9
Steudel 431 9 14.1 ± 2.6
Steudel 433 9 18.0 ± 2.1
Subsection Besseria
P. besseri Kessler 2989 1 20.4 ± 2.8 tetraploid / x = 12 or higher ploidy level
Kessler 2985 1 19.2 ± 1.9
P. crista-galli Beck 9343 1 16.6 ± 1.4 tetraploid / x = 12
Kessler 3155 1 17.8 ± 2.1
P. pallidistigma Boza 3005 9 17.2 ± 1.9 tetraploid / x = 12
Boza 3006 9 17.1 ± 2.2
Boza 3007 9 18.5 ± 1.9
Sylvester 1807 9 16.4 ± 1.4
Sylvester 1816 9 17.3 ± 1.9
Sylvester 1825 9 18.5 ± 1.9
P. rugulosa Ferreyra 2594 1 16.8 ± 1.9 tetraploid / x = 12
P. subtusalbida Beck 7395 9 22.1 ± 1.5 tetraploid / x = 12 and higher ploidy level
Kessler 216 9 23.4 ± 2.4
Ritter 1196 9 15.9 ± 1.4
Subsection Incanaee
P. fjeldsaoi Mendoza 1019 9 11.9 ± 2.6 diploid / x = 6
Mendoza 1032 9 13.3 ± 1.4
Mendoza 1057 9 15.2 ± 1.7
P. incana 3 ind. Sincholagua, Ec 6 1.99 ± 0.34 mainly diploid / x = 6 but also hexaploid / x = 18 (in cultivated plants only?)
3 ind. Illinizas, Ec 6 1.60 ± 0.14
3 ind. Inga-Raya, Ec 6 1.67 ± 0.30
3 ind. Cayambe-Coca, Ec (pl) 6 1.42 ± 0.10
3 ind. Antisana, Ec (pl) 6 4.67 ± 018
16 ind. El Ángel, Ec 2, 5, 6 (38 –) 42
6 ind. Illinizas, Ec 2, 5, 6 38
P. incana 30 ind. Cayambe-Coca, Ec 2, 5, 6 (39 –) 42
15 ind. Inga-Raya, Ec 6 42
15 ind. El Inga, Ec 4 40–42
15 ind. Papallacta, Ec 4 41–42
15 ind. El Ángel, Ec. 4 40–42
Laegaard 102647 1 17.6 ± 2.0
Schmidt-Lebuhn 521 1 17.0 ± 2.3
Illinizas, Ec 8 9.7 ± 0.5
Boza 3066 9 15.4 ± 1.8
Boza 3095 9 13.1 ± 1.5
Laegaard 102282 9 18.6 ± 2.2
P. incanoides Kessler 3288 1 16.4 ± 1.6 tetraploid / x = 12
Kessler 3293 1 18.3 ± 2.4
Beck 34512 9 15.3 ± 1.9
Kessler 2954 9 13.2 ± 0.7
P. nana Cult. Göttingen 1 2.93 ± 0.05 Cult. Göttingen 1 18.7 ± 1.7 tetraploid / x = 12; also lower ploidy levels ?
Cult. Göttingen 1 2.96 ± 0.05 Cult. Göttingen 1 19.6 ± 1.6
Kessler 3514 1 20.3 ± 2.6
Kessler 3642 1 19.5 ± 1.3
Kessler 3501 9 15.4 ± 1.8
Kessler 3518 9 13.1 ± 1.5
Kessler 3519 9 18.6 ± 2.2
P. tarapacana Cult. Göttingen 1 3.02 ± 0.17 Cult. Göttingen 1 ~80 Cult. Göttingen 1 17.4 ± 1.8 tetraploid / x = 12
Cult. Göttingen 1 3.00 ± 0.16 Cult. Göttingen 1 16.9 ± 2.3
Kessler 3599 1 17.4 ± 2.2
Kumar 6 1 17.1 ± 1.1
Beck 9008 9 14.9 ± 2.8
Beck 19897 9 16.1 ± 1.1
Beck 32470 9 15.0 ± 1.2
Boza 3009 9 14.9 ± 2.3
Kessler 3599 9 19.7 ± 2.0
P. tomentella 43 ind. Ar 7 2.90–3.01 Kessler 3188 1 17.9 ± 1.8 tetraploid / x = 12
Kessler 3368 1 18.7 ± 2.0
Boza 3107 9 16.6 ± 1.6
Boza 3110 9 13.9 ± 2.0
Boza 3111 9 15.3 ± 1.4
Kessler 3200 9 19.1 ± 2.5

Assigning ploidy levels to species of Polylepis can be based on two different base numbers. Segovia-Salcedo (2014) and Zurita et al. (2013) used the base haploid chromosome number of 7 in the family Rosaceae as reference, thus interpreting a chromosome count of 42 as hexaploid (x = 6). Schmidt-Lebuhn et al. (2010) and Kessler et al. (2014) instead used the lowest number in the genus (2n = 42) as baseline, interpreting this as functionally diploid. The evolution of chromosome numbers in angiosperms is highly complex, with repeated polyploidization events commonly followed by reductions in chromosome numbers via aneuploidy and dysploidy (de Wet 1971; Adams and Wendel 2005; Tate et al. 2005; Jiao et al. 2011; Weiss-Schneeweiss et al. 2013). We consider that, ultimately, within a plant group, the crucial factor is the behaviour of the chromosomes, i.e. whether they behave as bivalents so that during chromosome pairing each chromosome has a single counterpart or as polyvalents where they can pair with several other chromosomes. This behaviour is unknown for Polylepis or related genera. For simplicity, we here use a base chromosome number of 2n = 42 as baseline for defining diploids.

Based on this approach, for guard cell length, based on comparison with chromosome counts and genome size measurements, Boza Espinoza et al. (2020b) proposed that diploidy is related to guard cell lengths of 9–15 µm, tetraploidy to 14–20 µm and higher ploidy levels to 18–23 µm, showing that some overlap occurs that may make it difficult to assign a specific measure to a ploidy level. For genome size, the diploid condition is related to 2C values around 1.4–1.7 pg, triploidy to 2.0–2.3, tetraploidy to 2.6–3.4 pg, hexaploidy to 4.6–4.9 pg and octoploidy to 5.7–5.8 pg. Finally, chromosome counts of around 42 correspond to diploids, around 84 to tetraploids and around 126 to hexaploids. However, numerous published counts differ notably from these values. For example, Caiza et al. (2018) and Segovia-Salcedo and Quijia-Lamiña (2014) reported chromosome counts of 59–77 for nine individuals of P. ochreata (as P. sericea) from Yanacocha, Ecuador. In this situation, it is unclear if these numbers reflect the difficulty of fully counting the tiny chromosomes or whether they correspond to real values with would suggest triploidy and other intermediate chromosome levels as a result of aneuploidy and dysploidy.

At present, for the 45 species of Polylepis, combined data on guard cell length, chromosome number and genome size are available for nine (20%) species, on guard cell length and genome size for another nine (20%) species and on guard cell length and chromosome number for three (7%) species, whereas for 24 (53%) species, only guard cell measurements are available (Table 1). Bearing in mind the potential limitations of incomplete data and some uncertainty in the interpretation of the data, we infer that, at present knowledge, 19 (42%) species are purely diploid, 15 (33%) purely tetraploid and one (2%) purely octoploid. The remaining eight (18%) species have mixed ploidy levels, with three (7%) being di- and tetraploid, two (4%) di- and hexaploid, one (2%) tetra- and hexaploid, one (2%) tetra- and octoploid and one (2%) di-, tri-, tetra- and hexaploid. While it is likely that further studies will reveal more cases of mixed ploidy, at least some well-studied species appear to consistently show diploid (P. hieronymi, P. lanuginosa, P. simpsoniae) or tetraploid (P. tarapacana, P. tomentella) conditions.

Placing the ploidy levels in an evolutionary context, in section Sericeae, most species are diploid, but mixed di- and polyploidy is present in P. ochreata and P. pauta. These two species overlap in northern Ecuador where they hybridize extensively and it is conceivable that the polyploid condition stems from this hybridization, as polyploidy is often correlated with hybridization (de Wet 1971; Tate et al. 2005).

In section Reticulatae, again most species are diploid, but polyploidy occurs in P. microphylla and P. reticulata. Interestingly, at least in P. reticulata, polyploidy is only known only from cultivated plants (Segovia-Salcedo 2014), suggesting that this condition may be related to domestication.

In section Australes, P. australis has been well studied and includes di-, tri-, tetra- and hexaploids, most likely due to autopolyploidiation (Kessler et al. 2014). These ploidy levels show a clear geographical distribution pattern, with populations from the northern Argentinean Andes being purely diploid and those from the central Andes tetraploid, whereas in the isolated Sierra de Córdoba, all four ploidy levels co-occur in mixed populations. This suggests that the triploid plants may be hybrids between the di- and tertraploid ones, but whether they are sterile primary hybrids or can reproduce by themselves is unresolved. Additionally, the degree of reproductive isolation and, hence, evolutionary independence between the diploid and tetraploid populations remains unknown.

Sections Subsericantes and Incanaee mainly includes tetraploid species. These sections on average occur at higher elevations and in more arid environments than the other sections, which corresponds well with the polyploid condition, since polyploids are well known to be over-represented at high latitudes and elevations (Masterson 1994; Brochmann et al. 2004), possibly because the different paralogs offer more adaptive potential (Chung et al. 2010). In contrast to the dominant tetraploidy in these sections, both P. fjeldsaoi and P. incana are diploid. Polylepis incana has been considered to be one of the most derived species in section Incanaee (Simpson 1979, 1986; Schmidt-Lebuhn et al. 2006a), so that a diploid condition is surprising if one assumes that P. incana is nested within a tetraploid clade. This suggests that the assumption that P. incana is a derived member of this section is wrong and that the evolution of this section is more complex than previously assumed. In any case, assuming that the sections recognized here, based on morphological and ecological similarity, are evolutionary units, we now can deduce that polyploidy evolved at least five times in the genus, possibly more often. However, considering that the evolution of Polylepis is probably reticulate (Kerr 2004; Schmidt-Lebuhn et al. 2006a), inferring the origins of polyploidy in Polylepis may be very difficult.

Finally, focusing on the taxonomic implications of ploidy levels in the genus, we found that, in some cases, closely related species have different ploidy levels, supporting their treatment as distinct species. For example, P. fjeldsaoi has previously been identified as P. tomentella (Mendoza and Cano 2012), but whereas the first species is diploid, the latter is consistently tetraploid. On the other hand, at least eight species include individuals of different ploidy levels. At least in P. australis, this is clearly a natural condition (Kessler et al. 2014), which raises the question as to how to treat the different ploidy levels taxonomically. It has been suggested that different ploidy levels within a “species” should be treated at species level if there is morphological, ecological or biogeographical evidence that they are evolutionarily largely independent units (Soltis et al. 2007). This approach has been taken in polyploid-apomict species complexes of other genera of Rosaceae, such as Crataegus (Talent and Dickinson 2007) and Sorbus (Robertson et al. 2010), but more information is needed before this approach can be applied to Polylepis. On the other hand, in several species, polyploidization is apparently linked to cultivation, as in P. incana, P. racemosa and P. reticulata. Polyploidization of cultivated plants is a common phenomenon either via auto- or allopolyploidization where higher ploidy levels are often associated with higher plant vigour and adaptive potential (Paterson 2005; Matsuoka 2011; Sattler et al. 2016). Polylepis has long been planted by Andean inhabitants as a source of building material, firewood and as fences (Kessler 1995d) and it is conceivable that natural or artificial hybrids have been favoured. For a more detailed discussion of this situation in P. racemosa, see under that species.

Phylogenetic reconstructions

Polylepis belongs to the tribe Sanguisorbeae DC., which is characterized by cup-shaped hypanthium that entirely encloses the carpel(s), resulting in a perigynous position of the flower (Focke 1894; Robertson 1974; Eriksson et al. 2003; Potter et al. 2007). Polylepis has long been placed in close taxonomic proximity to Acaena, a genus of some 100 species of mainly evergreen, creeping herbaceous perennial plants and subshrubs found mostly in New Zealand, Australia and South America, with a few species extending to Hawai’i and California. Previously, Bitter (1911) argued for a derivation of Polylepis from a species group in Acaena that includes A. elongata because this group is characterized by multipinnate leaves and long dense racemes similar to those of Polylepis. Bitter (1911) also implicitly considered that the most ancestral species of Polylepis may be P. multijuga because it has long dense racemes and spine-covered fruits reminiscent of those of Acaena.

Simpson (1979, 1986) provided the first explicit ideas about the evolution of Polylepis, placing the species in three informal groups. The first of these groups, the sericea group (here section Sericeae), includes species with putatively ancestral traits such as large, multipinnate leaves with thin texture, and long inflorescences with numerous flowers. Most species of this group grow at relatively low and often humid conditions at the upper margin of the cloud forest, where Acaena also occurs. The second group is the reticulata group (our section Reticulatae), characterized by nitid, emarginated leaflets with pannose undersides of the leaflets. The species of this group occur at higher elevations than those of the first group and often also in more arid habitats. Finally, the large incana complex (our sections Australes, Subsericantes and Incanaee) is morphologically quite variable (which is why we placed the species in three sections), but includes many species with just one leaflet pair, densely pannose or even glandular lower leaflet surfaces and highly reduced inflorescences. While some species occur at low elevations and in humid regions, many are found in rather arid habitats and often at very high elevations. Simpson (1986) concluded that Polylepis likely originated from Acaena under humid cloud forest conditions and from there, gradually expanded its ecological amplitude to reach highly arid and cold environments of the high Andes, not accessible to any other native tree genus. This evolutionary trend was paralleled by morphological changes including reductions in growth height, leaflet size, number of leaflets, inflorescence length and number of flowers and an increase in leaf thickness. In the next study commenting on the evolution of the genus, Kessler (1995a) largely followed Simpson’s views.

The first attempt to study the evolutionary history of Polylepis using molecular methods was undertaken by Malin Kerr in an unfortunately largely unpublished PhD thesis (Kerr 2004). Using the chloroplast markers trnL/F and Ahd1, as well as a nuclear ITS locus of over 50 accessions of Polylepis, 26 accessions of Acaena and numerous other Rosaceae, she was able to confirm that Polylepis is nested within Acaena, rendering the latter genus paraphyletic. Based on her limited sampling, Kerr (2004) hypothesized that Polylepis, as a whole originated, from a hybridization event between ancestral members of the Acaena elongata and A. cylindristachya species groups. She hypothesized that this hybridization event was probably allopolyploid, as suggested by her understanding that Acaena has a predominant ploidy level of 2n = 42 in Acaena, whereas Polylepis in her view has 2n = 84. However, we now know that 2n = 42 is also common and presumably ancestral in Polylepis (see Ploidy levels). Still, morphologically Polylepis combines traits of both the A. elongata group (spiny fruits) and the A. cylindristachya group (racemose inflorescences), supporting the idea of a hybrid origin of Polylepis. However, to complicate matters, Kerr (2004) also found indication that P. quadrijuga later hybridized with a member of Acaena section Ancistrum (to which neither A. elongata nor A. cylindristachya belong). However interesting, the conclusions of Kerr (2004) were based on limited sampling and the use of the nuclear marker ITS which is notorious for having multiple copies, especially in polyploidy plants, potentially hampering phylogenetic reconstructions (Baldwin et al. 1995).

The second attempt at a molecular phylogenetic reconstruction of Polylepis was undertaken by Schmidt-Lebuhn et al. (2006a), based on 46 accessions of Polylepis and two accessions of Acaena using Amplified Fragment Length Polymorphisms (AFLP) of primarily the nuclear genome. Their results were quite similar to those obtained by Kerr (2004): very limited resolution within the genus and strong geographical clustering of the accessions, to the degree that samples of the same species would cluster with geographically proximate samples of other species rather than with their conspecifics. Combining this data with a morphological data matrix, they nevertheless obtained a phylogenetic hypothesis that clustered similar species in meaningful groups. These groups largely corresponded to Simpson’s (1979, 1986) classification: a basal grade corresponding to the sericea group (our section Sericeae), a monophyletic reticulata group (section Reticulatae), and a monophyletic incana group (sections Australes, Subsericantes and Incanaee) with P. subsericans as sister to the other species in the group. The latter species was placed by Simpson (1979) in her sericea group, but she commented on the intermediacy of the species between the sericea and incana groups and we here place it in a section of its own, together with two other species.

The latest molecular study of the phylogeny of Polylepis was conducted by M. Claudia Segovia S. in a PhD thesis that also remains largely unpublished (Segovia-Salcedo 2014). She used Next Generation Sequencing (Hyb-Seq) to analyze 256 nuclear genes and chloroplastic genomes of 25 Polylepis accessions. Her phylogenetic reconstruction showed a strong geographical signal and recovered groups of morphologically very different species that did not correspond to the groups proposed by Simpson (1979, 1986) and Schmidt-Lebuhn et al. (2006a). As Segovia-Salcedo (2014) did not include replicate samples of widespread species, it is impossible to assess whether samples of the same species from different geographical areas would be recovered close to each other in a phylogenetic reconstruction.

In conclusion, our understanding of the evolutionary history of Polylepis is still very incomplete. While morphological traits point to a plausible story of diversification and adaptation from humid cloud forests to arid high-elevation habitats, molecular data suggest a complex, reticulate evolutionary history. Additionally, while there is evidence that Polylepis is nested within Acaena, we refrain from merging both genera until a clearer picture of their evolutionary relationships emerges.

Implication for species delimitation

Based on all the above, we can conclude that there is ample gene flow between populations of Polylepis assigned to different species. Although species can be distinguished on morphological, biogeographical and ecological grounds, it is likely that gene flow between populations of different species in close proximity have more gene flow between them than geographically remote populations of the same species. At the same time, the presence of different ploidy levels in at least eight species of the genus suggests that there may be barriers to gene flow within species.

In such a situation, the classical biological species concept of species being reproductively and evolutionarily independent units is hardly applicable (Mayr 2000). Polylepis may, thus, be a case where a genic species concept, rather than a genomic species concept is more appropriate. The genic species concept (Wu 2001) assumes that species identity is based on relatively few gene regions that determine the fundamental physiological or morphological traits that define a species and that the remainder of the genome can be exchanged between species without compromising species identity. In this view, species identity is not dependent on full reproductive isolation, but rather is determined by selection on relatively few genes. In contrast, the genomic species concept is based on the traditional view of reproductive isolation between species, leading to genetic divergence across the entire genome (Lexer and Widmer 2008). For Polylepis, all of this remains speculative and detailed genomic studies are needed to confirm the speciation mode in the genus.

Ecology

Polylepis may well be the ecologically best-studied Andean tree genus. This is because it reaches the highest elevations of any tree genus in the Andes and because Polylepis forests are among the most threatened ecosystems in the neotropics. In the following, we briefly review some aspects of the physiology, ecology, and biogeography of Polylepis as they are relevant for our monographic work.

Physiological adaptations

Polylepis typically forms the uppermost forest belt in the tropical Andes, although some species also grow at lower elevations in mixed forest stands with other tree genera. Due to the high elevations and accordingly low temperatures at which these trees occur, they have been the focus of a number of ecophysiological studies aiming to understand the adaptations to low temperatures. However, since the 45 species inhabit a wide range of habitats, ranging from moderate to extremely high elevations and arid to superhumid environments, the different species express a wide range of physiological adaptations that go beyond only adaptations to low temperatures.

The ability to tolerate the low nocturnal temperatures that are typical of tropical mountains is, in some species, achieved by daily osmotic adjustments and supercooling down to -9 °C as in P. sericea or freezing tolerance as in P. australis and P. tarapacana (Rada et al. 1996, 2001, 2009; Azócar et al. 2007). In the latter two species, leaf tissue freezes at temperatures between -3.5 °C and -9.2 °C, but frost injury is only observed at temperatures between -18 °C and -24 °C.

Adaptations to drought conditions are also frequent in Polylepis and include small, thick leaflets with wax layers and sunken stomata to reduce transpirational water loss (Macek et al. 2009). This is most clearly seen in P. tarapacana (García-Núñez et al. 2004; Toivonen et al. 2014). In arid areas at high elevations, solar radiation is very intense, leading to the development of protective pigments (González et al. 2007).

Photosynthetic rates of Polylepis range from 3 μmol·m-2·s-1 in P. tarapacana to 9 μmol·m-2·s-1 in P. australis (Azócar et al. 2007). Species inhabiting relatively low elevations with higher temperatures have higher mass-based maximum photosynthesis, stomatal conductance and leaf area than species from the higher and colder habitats (Toivonen et al. 2014). Conversely, species from humid habitats, where water stress is low, but where clouds and fog often reduce insolation, have higher light use efficiency and lower light saturation and compensation points (Toivonen et al. 2014).

Generally speaking, physiological traits in Polylepis are related either to the temperature or precipitation conditions at which they grow, revealing evolutionary specialization and adaptation of the species along environmental gradients.

Reproduction and growth

Polylepis is wind-pollinated. Although most pollen is deposited at close distances to the trees (Kuentz et al. 2007), pollen flight of up to 80 km has been documented (Seltmann et al. 2009a), suggesting extensive gene flow between populations (see Pollination biology and seed dispersal). In P. australis, there is increased mortality in offspring resulting from short-distance crosses and increased vigour (N-metabolism capacity) in long-distance crosses, providing evidence for inbreeding depression (Seltmann et al. 2009b).

The seeds of Polylepis are not well adapted for long distance dispersal. Species in section Sericeae have spines that allow them to be transported in the fur of animals, but nothing is known about dispersal distances. In many other species, the nutlets have spiny ridges that do not appear to be adapted to any specific dispersal type (Simpson 1986) and which mostly accumulate close to the parent trees. Only P. australis and P. neglecta (section Australes) have thin wings apparently adapted to wind dispersal, but flight distances are only up to a few dozen meters (Renison et al. 2004).

Polylepis seeds typically have low germination rates, possibly associated with dormancy (Cuyckens et al. 2021) and seed germination is temperature-dependent, with maximum germination at about 20 °C in P. besseri (Gareca et al. 2012), which is relatively high for high mountain environments. Accordingly, regeneration by seeds often decreases with low temperatures at high elevations (Byers 2000; Hoch and Körner 2005; Gareca et al. 2007; Hertel and Wesche 2008; Wesche et al. 2008). This may be a result of decreasing germination, but also of reduced seed production (Cierjacks et al. 2008). In arid habitats, such as northern Chile, successful reproduction may only occur in exceptionally favourable (humid and warm) years, leading to the formation of age cohorts (Rundel et al. 2003).

The species of Polylepis are generally rather slow-growing, with radial growth rates typically in the order of 1 mm per year, although much variation exists (Domic and Capriles 2009; Jomelli et al. 2012; Montalvo et al. 2018). On the other hand, under optimal conditions, young trees can achieve height increments of up to 50 cm per year, especially in P. racemosa, which is the most commonly cultivated species because of its fast growth (Rosero et al. 2018). Tree height in Polylepis commonly decreases with elevation, but, in arid valleys, can also decrease at low elevations due to drought (Cierjacks et al. 2008; Hertel and Wesche 2008; Kessler et al. 2014). However, tree height is also influenced by more local conditions, so that, in arid regions, shaded (and hence more humid slopes) have taller trees (Kessler et al. 2007). In many forests, tree height is also limited by human extraction of tall trees (Toivonen et al. 2011; Kessler et al. 2014).

Dendrochronological studies on P. tarapacana in Bolivia suggest tree longevity of at least 700 years, with precipitation being positively and high summer temperatures (which increase drought stress) negatively related to radial growth (Argollo et al. 2004; Morales et al. 2004). Growth rates in this species decrease with elevation, but are higher in sheltered microhabitats (Domic and Capriles 2009). In P. besseri, radial growth is limited by the accumulation of reserves the year before ring formation, with a warm period before the growing season (humid period) increasing growth (Gareca et al. 2010). In Polylepis australis, tree vitality and growth are highest in the middle of the elevational distribution of the species, being limited at low elevations by high temperatures and drought, and at high elevations by low temperatures (Marcora et al. 2008). This species has lower growth when surrounded by rocks (Suarez et al. 2008). Such local control of growth has also been observed in P. pepei in Bolivia, where it is influenced by slope and substrate (moraine or scree slope) (Jomelli et al. 2012).

Habitat associations

One the most conspicuous patterns in the distribution of Polylepis forests is that, frequently, they occur as isolated forest patches isolated from the closed treeline (Herzog 1923; Troll 1959; Hueck 1962; Vareschi 1970; Kessler 2002). It has long been debated whether this is a natural or human-induced pattern. Especially, earlier authors have argued that these patches occur in microclimatically favoured habitats, especially boulder slopes (Raimondi 1874; Weberbauer 1907, 1930; Herzog 1923; Troll 1929; Herrera 1943; Barreda 1951; Koepcke 1961; Cerrate 1979; Arnal 1983; Salgado-Laboriau et al. 1984; Ferreyra 1986). Walter and Medina (1969) proposed that boulder slopes allow warm air to penetrate deeper into the soil, allowing for better root development. However, soil temperature measurement by Kessler and Hohnwald (1998) have shown that boulder slopes are actually colder than adjacent fine-grained soils, as also known from other mountain regions (Wakonigg 1996). As an alternative explanation, Ellenberg (1958) proposed that rocky ground prevents the spread of fires and thus allows the survival of forests. The negative influence of fires has been documented by subsequent studies (Lægaard 1992; Kessler 2000; Kessler et al. 2014). Often, this also leads to a concentration of Polylepis stands to sheltered ravines and along watercourses (Weberbauer 1911; Troll 1959; Salgado-Laboriau et al. 1984; Rauh 1988).

Current understanding of this so-called “Polylepis-problem” suggests that the natural vegetation pattern would be a grassland-forest mosaic, with increasing grassland contribution towards higher elevations (Toivonen et al. 2011, 2018; Sylvester et al. 2014a, 2017). Nevertheless, because of the paucity of undisturbed habitats, it is not known which conditions determine the development of forest or grassland in these mosaics. Factors may involve water saturation of soils, cold air ponding or strong winds (Kessler 1995d; Sparacino et al. 2020). It is known, however, that unless fires further push the forests back (Kessler 2000), the expansion of forests into grasslands is very slow due to the low ability of Polylepis to colonize dense grasslands (Cierjacks et al. 2007a), suggesting that the forest-grassland mosaics are fairly stable over time.

Other habitat associations of Polylepis include a preference for cloud condensation belts in arid regions (Troll 1959; Koepcke 1961; Lauer 1982; Cabido and Acosta 1985) and avoidance of salty soils (Kessler 1995d). Beyond these general patterns, there are many species-specific habitat preferences. For instance, whereas most species of Polylepis form the canopy layer of the forests, P. hieronymi is a successional species that often colonizes raw soils on landslides and road banks and is then displaced by taller trees, such as Podocarpus parlatorei (Kessler 1995b).

The upper limit of the growth of Polylepis forests has been a matter of some debate. Jordan (1980) claimed that P. tarapacana reaches 5200 m on Volcán Sajama, but subsequent studies have highest trees (3 m tall) at 4820 m, with only shrubby plants reaching 5000 m (Hoch and Körner 2005). Similar elevations are reached by P. subsericans in Cuzco, Peru (S. Sylvester, pers. comm.) and P. weberbaueri in Ancash, Peru (T. Boza, pers. obs.). Along with Juniperus tibetica forests at 4900 m in Tibet, these are the world’s highest forests (Miehe and Miehe 1994).

History of Polylepis forest cover

It is generally accepted that the genus Polylepis evolved in the Andes from the genus Acaena (Simpson 1986). The age of the genus is unknown, but the oldest available pollen records show that it was already present 370,000 bp (years before present) in Peru and Bolivia (Hanselman et al. 2011) and 124,000 bp on the Bogotá Plateau, Colombia (van der Hammen and Hooghiemstra 2003). These and other more recent pollen records show that the pollen abundances of Polylepis varied substantially over time, suggesting that forest cover changed over time even prior to the arrival of humans about 12,000 bp. These fluctuations have been linked to climatic changes, with warm and wet periods being correlated with maximum Polylepis abundance (Gosling et al. 2009). Opposed to this, natural fires, especially during dry periods, reduced Polylepis cover. Polylepis forest cover was also patchy due to landscape heterogeneity with, for instance, flat valley bottoms with water-logged soils being devoid of tree cover (Gosling et al. 2009; Valencia et al. 2018). During arid and cold climatic phases, forests were, thus, restricted to climatic microrefugia, such as sheltered valleys (Valencia et al. 2016). Similar forest-grassland mosaics can currently be found in topographic refugia inaccessible to humans and their livestock (Sylvester et al. 2014a, 2017). That some Polylepis species had a natural fragmented distribution is also evidenced by geographic patterns of genetic diversity, as, for example, in P. tarapacana (Peng et al. 2015).

The arrival of humans increased fire frequencies, first by hunter-gatherers and later by agropastoralists with their livestock, leading to widespread reductions in Polylepis abundance (e.g., Graf 1979, 1981, 1983, 1992; Hansen et al. 1984; Ybert and Miranda 1984; Markgraf 1985; Hansen 1992; Baied and Wheeler 1993; Chepstow-Lusty et al. 2005; Urrego et al. 2011; Williams et al. 2011). For example, in Cochabamba, Bolivia, at a site where today P. lanata and P. pepei occur in small patches above the closed treeline, Polylepis forests were more widespread some 18,000–14,500 a bp, declining towards some 10,000 a bp, followed by a period almost without Polylepis until 6,400 a bp, followed by slight increase to current levels (Williams et al. 2011). These changes in the abundance of Polylepis were linked to changes in fire frequency, partly due to dryer climatic conditions and partly due to human activities.

In southernmost Ecuador, at the border with Peru, Polylepis populations are currently restricted to tiny populations, but pollen evidence shows that Polylepis was much more common in the early to mid-holocene (about 11,000–4,000 bp) (Rodríguez and Behling 2012; Villota and Behling 2013). Later, as climatic conditions became more humid and human impact led to increasing fire frequencies, Polylepis declined massively, being replaced by mixed humid montane forest and grassland.

The development of human cultures in the Andes took an important step forward some 6,000 bp with the domestication of camelids (Wing 1986; Wheeler 1985, 1988). The development of large-scale pastoralism led to the widespread ecosystem degradation (van der Hammen and Noldus 1985; Thompson et al. 1988). During the Incan period, up to 30 million people may have inhabited the central Andes (Earls 1976). An important component of this land use was the development of agroforestry (Chepstow-Lusty and Jonsson 2000; Chepstow-Lusty et al. 2009; Chepstow-Lusty 2011; Mosblech et al. 2012), including reforestation with Alnus in the last 1000 years (Chepstow-Lusty et al. 1998). After the Spanish conquista, forest destruction picked up again and continues until today in many regions (Jameson and Ramsay 2007).

Biotic interactions

Polylepis forests harbour unique biodiversity, including a number of highly specialized, often range-restricted and threatened bird species (Fjeldså 1993; Cahill and Matthysen 2007; Lloyd 2008a; Astudillo et al. 2020; Quispe-Melgar et al. 2020). However, these birds generally do not influence the trees themselves, except for the Thick-billed Siskin (Spinus crassirostris), which eats the seeds of Polylepis without dispersing them (Herzog et al. 2003).

Polylepis forests also provide habitats for many plant species, including the world’s highest vascular epiphytes (Sylvester et al. 2014b) and a diverse liverwort flora (Gradstein and León-Yañez 2020; Gradstein and Pócs 2021). Nothing is known of competitive or facilitative interactions with other plant species in the germination, seedling or growth stages. However, many populations of Polylepis species are parasitized by Tristerix chodatianus (Loranthaceae), a specialist hemiparasite that infects trees of the genus Polylepis (Amico et al. 2007). In P. flavipila forests, up to 48% of the trees can be infected, which leads to the death of branches about 15 years after infestation and, in heavily infested trees, eventually to the death of the whole tree (Arizapana et al. 2016; Camel et al. 2019b).

Fungal interactions are also important in Polylepis (Robledo and Renison 2010). Polylepis australis has vesicular arbuscular mycorrhizal symbionts (Menoyo et al. 2007, 2009; Soteras et al. 2013). The same is presumably true for all other species, but this remains to be studied. Polylepis tarapacana is parasitized by the fungus Paraleptosphaeria (= Leptosphaeria) polylepidis (Leptosphaeriaceae, Pleosporales), which appears to lead to increased tree mortality (Macía et al. 2005; Coca-Morante 2012). Interestingly, this fungus, in turn, is infected by the mycoparasite Sajamaea mycophila (Dictyosporiaceae, Pleosporales), which may perhaps be used as a biocontrol of P. polylepidis (Piątek et al. 2020). In P. tomentella, species of three genera of Ascomycota have been found in stigmas and styles, which appears to negatively affect the germination of pollen grains by inhibiting pollen tube growth, although the fungi apparently are not able to penetrate the ovary (Domic et al. 2017).

Conservation

Polylepis forests represent one of the most endangered habitats in the high Andes (Hensen 2002; Servat et al. 2002; Rundel et al. 2003; Navarro et al. 2005; Kessler and Schmidt-Lebuhn 2006; Cierjacks et al. 2008; Mendoza and Cano 2012; Boza Espinoza et al. 2019; Segovia-Salcedo et al. 2021). It has been estimated that over 90% of Polylepis forests have already been lost in Peru and Bolivia (Kessler 1995d; Fjeldså and Kessler 1996). Major threats caused by human activities include logging, chronic overgrazing and burning (Fjeldså 2002b; Renison et al. 2002; Boada and Campaña 2008; Cierjacks et al. 2008; Navarro et al. 2010; Renison et al. 2011; Renison et al. 2013; Sylvester et al. 2016) and more locally the expansion of the agricultural frontier and mining activities (Rundel et al. 2003; Guerrero 2009; Sornoza-Molina et al. 2018). These activities have taken place long before the arrival of European conquerors and likely have affected Andean ecosystems for millennia (Kessler and Driesch 1993; Kessler 1995d). On the other hand, the Andes are expected to undergo severe changes in the coming decades as a result of on-going land-use change and climate change (Malcolm et al. 2006; Beaumont et al. 2011), likely threatening Polylepis forests even more. Polylepis forests have a low ability to colonize dense grasslands and low seed dispersal ability, severely limiting the ability of the forests to spread and to track climatic conditions (Cierjacks et al. 2007a). Fragmentation of Polylepis forests often, but not always, leads to loss of genetic diversity, which is even evident from one generation to the next (Julio et al. 2008, 2011; Aragundi et al. 2011; Hensen et al. 2012; Quinteros-Casaverde et al. 2012; Gareca et al. 2013; Peng et al. 2015, 2017). As a result of all the above, Polylepis forests have been listed as one of the most endangered woodlands ecosystems in the world (UNEP-WCMC 2004) and the conservation of the remaining forests stands has been given high priority (Kessler 1995d; Fjeldså and Kessler 1996; Cierjacks et al. 2008).

Conservation of Polylepis forests is not only relevant for the trees themselves. The forests are rich in endemics species and represent hotspots of biodiversity (Fjeldså and Kessler 1996; Fjeldså and Hjarsen 1999; Sevillano-Ríos and Rodewald 2017). Many studies have been dedicated to the floristics, structure, distribution and biology of Polylepis forests in Ecuador, Peru and Bolivia (e.g., Hensen 1993, 1995; Kessler 1995a, b; Fjeldså and Kessler 1996; Cierjacks et al. 2007a; Cierjacks et al. 2007b; ECOAN 2005, 2006, 2007; Jameson and Ramsay 2007; Ames-Martínez et al. 2019). Additionally, the unique bird communities associated with Polylepis forests have been studied in much detail (e.g. Fjeldså 1987; Frimer and Nielsen 1989; Fjeldså 1992; Fjeldså and Kessler 2004; Lloyd 2008a, b; Lloyd and Marsden 2008).

In this context, the evaluation of the conservation status and the degree of threat to the species is necessary in order to successfully focus conservation action. Although the current online version of the IUCN Red List of Threatened Species (http://www.iucnredlist.org/) presents assessments of species of the genus Polylepis, it includes barely 15 species, with 14 species listed as “Vulnerable” (VU) and one as “Near Threatened”. Bearing in mind the novel taxonomic arrangement proposed here, we present a global assessment of the conservation status for the 45 species of Polylepis, applying the IUCN Criteria and Categories (Table 3). As a result, we categorize over four fifths of the species of Polylepis as threatened, with almost half of the species categorised as “Vulnerable” (47%), 24% as “Endangered” and 18% as “Critically Endangered”, but only 9% as “Least Concern” and 2% as “Near Threatened”.

Table 3.

Conservation status of Polylepis species. Abbreviations: Ar = Argentina, Bo = Bolivia, Ch = Chile, Co = Colombia, Ec = Ecuador, Pe = Perú, Ve = Venezuela.

Species Status Criteria Country Conservation Areas
Section Sericeae
Subsection Lanuginosae
P. lanuginosa EN B1a+B2a, C1 Ec Cajas National Park
P. multijuga CR A1, B1a+B2a, C1 Pe None
Subsection Pauta
P. pauta VU A1, B1a+B2a, C1 Ec Cayambe-Coca National Park
Antisana Ecological Reserve
P. longipilosa CR A2a, B1a+B2a, C1+C2 Ec El Angel Ecological Reserve
P. serrata VU B1a+B2a, C1 Pe Río Abiseo National Park
Manu National Park
Subsection Sericeae
P. albicans VU B1a+B2a Pe Huascarán National Park
P. argentea VU B1a+B2a Pe Otishi National Park
P. canoi EN B1a+B2a, C1 Bo, Pe Otishi National Park
P. frontinensis CR B2ac, C2a Co Colibrí del Sol Private Reserve
P. humboldtii CR B2a, C2 Ec Sangay National Park
P. longipilosa CR A2a, B1a+B2a, C1+C2 Ec El Angel Ecological Reserve
P. loxensis CR A2a, B1a+B2a, C2a Ec None
P. ochreata VU B1a+B2a, C1 Co, Ec El Angel Ecological Reserve (Ec)
Yanacocha Reserve (Ec)
P. sericea VU B1a+B2a Co, Ve Sierra Nevada National Park (Ve)
Sierra de la Culata National Park (Ve)
Subsection Pepea
P. pepei EN A2a, B1a+B2a, C1, D1 Bo, Pe Madidi National Park (Bo)
Carrasco National Park (Bo)
P. rodolfo-vasquezii VU B1a+B2a, C1 Pe Pui-Pui Protection Forest
Section Reticulatae
P. hieronymi VU B1a+B2ac Ar, Bo Cordillera de Sama Biological Reserve (Bo)
P. microphylla EN B1a+B2ab Ec, Pe Sangay National Park (Ec)
Cordillera Huayhuash Reserved Zone (Pe)
P. occidentalis EN A1, B1a+B2a, C1 Pe None
P. quadrijuga VU A2a, B1a+B2a, D2a Co Chingaza National Natural Park
Cocuy National Park
Sumapaz National Natural Park
P. reticulata VU B1a+B2a, C1 Ec Cajas National Park
Llanganates National Park
Pasochoa Ecological Reserve
Yacuri National Park
P. simpsoniae EN A1, B1a+B2a, C2a Ec Cajas National Park
P. weberbaueri VU B1a+B2a Pe Huascarán National Park
Section Australes
P. australis LC B1a+B2a Ar Quebrada del Condorito National Park
P. neglecta VU A1,2a, B1a+B2a, C2a Bo None
Section Subsericantes
P. flavipila EN B1a+B2a, C2a Pe Nor Yauyos-Cocha Landscape Reserve
P. pilosissima CR A2a, B2a Pe Japani Private Conservation Area
P. subsericans VU B1a+B2a Pe Vilcanota Private Conservation Areas Network
Section Incanaee
Subsection Racemosae
P. acomayensis EN A2a, B1a+B2a, C2a Pe None
P. incarum CR A1, B1a+B2a, C1+C2a Bo, Pe None
P. lanata VU B1a+B2a, D2a Bo Carrasco National Park
P. pacensis EN A2b, B1a+B2a, C1 Bo None
P. racemosa LC B1a+B2a Ec, Pe None
P. sacra VU B1a+B2a Pe Vilcanota Private Conservation Areas Network
P. triacontandra EN A1, B1a+B2a, C1 Bo, Pe Apolobamba Integrated Management Natural Area (Bo)
Subsection Besseria
P. besseri VU A1, B1a+B2a, C1 Bo None
P. crista-galli VU A1, B1a+B2a, C2a Ar, Bo None
P. pallidistigma VU B1a+B2a Pe None
P. rugulosa VU B1a+B2a, C1 Ch, Pe Lauca National Park (Ch)
Islunga National Park (Ch)
Las Vicuñas National Reserve (Ch)
Salinas y Aguada Blanca National Reserve (Pe)
P. subtusalbida VU A1, B1a+B2a Bo Tunari National Park
Subsection Incanaee
P. fjeldsaoi VU B1a+B2a, C2a Pe None
P. incana LC A1, B1a+B2a Co, Ec, Pe Cajas National Park (Ec)
Illinizas Ecological Reserve (Ec)
El Angel Ecological Reserve (Ec)
Huascarán National Park (Pe)
Cordillera Huayhuash Reserve Zone (Pe)
P. incanoides EN A1+A2a, B1a+B2a, D1 Bo None
P. nana CR A1+A2a, B1a, C1+C2a, D2a Bo None
P. tarapacana NT A1+A2a, B1a+B2a, C1 Ar, Bo, Ch, Pe Sajama National Park (Bo)
P. tomentella LC A1, B1a+B2a, C2a Ar, Bo None

Most of the species of Polylepis are present in at least one protected area, but 16 species have no such conservation actions taken to date. However, actual protection of the species in conservation areas leaves much to be desired. In many cases, no specific conservation actions are taken, in others, extractive activities continue within protected areas. Even where reforestation schemes are undertaken, these are often counterproductive, since alien species of Polylepis are used which can hybridize with the native species. For instance, P. racemosa is not native to Ecuador, but has been widely planted and is already hybridizing with the native species.

More generally, there is mixed success of protected areas in conservations terms which may show the limitations of strictly conservationist approaches that fail to take into consideration the needs of local human population (Joseph et al. 2021). Identification of development alternatives that reduce firewood collection and free-ranging ranching and implementation of a sustainable development plan are measures that may help to save these unique vegetation types. Such attempts have been undertaken, for example, for P. australis in Argentina, where restoration activities are tightly coupled with detailed research activities (Renison et al. 2002, 2004, 2005, 2006, 2010, 2011; Teich et al. 2005; Menoyo et al. 2007; Seltmann et al. 2007, 2009a, b; Julio et al. 2008, 2011; Suarez et al. 2008; Torres et al. 2008; Zimmermann et al. 2009; Giorgis et al. 2010; Peng et al. 2017). Since 2018, the NGOs Andean Ecosystem Association (ECOAN) and Global Forest Generation (GFG) have joined forces to create long-term alliances with partners in Colombia, Ecuador, Peru, Bolivia, Argentina and Chile within the Andean Action initiative. This initiative strengthens leadership capabilities and enhances the conservation, research and restoration of Polylepis forests through collective work and stable commitment to local communities and authorities. The goal is to restore and protect one million hectares of high Andean forests through effective and remunerable actions. This clearly is a pivotal time for the conservation of Polylepis forests, with increasing threats and increasing conservation activities.

Taxonomic treatment

Polylepis Ruiz & Pavón (1794:80)

Type

Polylepis racemosa Ruiz & Pavón.

Description

Trees or shrubs 1–32 m tall; bark shredding, multilayered with thin exfoliating layers; branches twisted showing a striking arrangement of the leaves, young shoots with leaves usually all closely clustered at the top, causing a shrub-like growth, while the basal internodes stretch rather significantly afterwards. Leaves alternate, imparipinnate with 1–7 pairs of lateral leaflets, obtrullate in outline, 1.3–19.5 cm long, 0.6–10.7 cm wide; rachises lanate, pannose, sericeous, tomentose, villous or glabrous; point of leaflet attachment with a tuft of long hairs; stipular sheaths apically acute, truncate or spurred, glabrous to densely covered with lanate, tomentose or villous hairs on the other surface; leaflets elliptic, ovate or obovate in outline, 0.3–5.4 cm long, 0.2–2.0 cm wide; margins entire, revolute, crenate to serrate, apically acute to deeply emarginate, attenuate, cuneate or unequally cordate, upper leaflet surfaces glabrous or sparsely to densely lanate, pilose, sericeous or tomentose; lower leaflet surfaces covered with very short pannose hairs, pannose mixed with another type of hairs or sparsely to densely lanate, pilose, sericeous, strigose, tomentose or villous. Inflorescences axillar, simple rarely branched, upright or pendant to 36.0 cm long, bearing 1–83 flowers; floral bracts 2.1–15.8 mm long, narrowly triangular. Flowers hermaphroditic; sepals 3–4; stamens 5–27, anthers orbicular with a dense tuft of straight white hairs in the upper half; styles fimbriate, 0.9–4.9 mm long, ovary inferior; carpel 1, ovule 1. Fruit indehiscent achene, fusiform turbinate with protuberances, flattened-spines, irregular flattened ridges, thick wings and ridges or thin wings, glabrous to densely sericeous, tomentose or villous, 1.7–15.1 mm long, 1.3–10.1 mm wide including spines.

Key to species of the genus Polylepis

1 Lateral leaflets 1 pair 2
Lateral leaflets 2–7 pairs 21
2 Lower leaflet surfaces densely pannose, hairs < 0.2 mm long 3
Lower leaflet surfaces sparsely to densely pilose, sericeous, strigose, tomentose or villous, hairs 0.4–2.0 mm long 10
3 Leaflet margins crenate 4
Leaflet margins entire or serrate 6
4 Stipular sheaths apically acute, outer sheath surfaces densely villous P. incana
Stipular sheaths apically truncate, outer sheath surfaces glabrous to densely villous 5
5 Leaflets obovate; upper leaflet surfaces and rachises tomentose; central Peru P. fjeldsaoi
Leaflets elliptic; upper leaflet surfaces and rachises villous; southern Peru P. pallidistigma
6 Leaflets 0.7–1.2 cm long; inflorescences 0.7–1.5 cm long 7
Leaflets 1.3–3.2 cm long; inflorescences 2.2–8.0 cm long 8
7 Leaflets 1.0–1.2 cm long; upper leaflet surfaces often with dark sheen, glabrous to sparsely villous; central Bolivia P. nana
Leaflets 0.7–0.8 cm long; upper leaflet surfaces rugose, glabrous, usually covered with a layer of yellowish resinous exudate; south-western Peru, north-western Chile, western Bolivia and north-western Argentina P. tarapacana
8 Stipular sheaths with outer surfaces densely tomentose; 13–15 stamens per flower; fruits with 2–4 wide flattened hard irregular ridges, sparsely tomentose P. crista-galli
Stipular sheaths with outer surfaces glabrous to densely villous; 15–23 stamens per flower; fruits with 3–4 ridges with a variable number and placement of flattened spines, densely villous 9
9 Leaflets 0.5–0.7 cm wide, with 7–15 teeth per side; leaflet apices obtuse to slightly acute; upper leaflet surfaces glabrous; 5–7 flowers per inflorescence; 15–19 stamens per flower; Dpto. Cochabamba (Bolivia) P. incanoides
Leaflets 0.3–0.6 cm wide, with 5–10 teeth per side, leaflet apices round to emarginate; upper leaflet surfaces glabrous to sparsely villous; 4–5 flowers per inflorescence, 19–23 stamens per flower; Dptos. Potosi, Oruro, Chuquisaca, Tarija (Bolivia) and Jujuy (Argentina) P. tomentella
10 Leaflet margins serrate 11
Leaflet margins entire or crenate 13
11 Lower leaflet surfaces sparsely to densely tomentose without underlying short hairs; 7–21 flowers per inflorescence P. racemosa
Lower leaflet surfaces densely tomentose with a dense underlying layer of very short white hairs; 3–7 flowers per inflorescence 12
12 Leaflets 0.7–1.3 cm wide; leaflet apices acute; inflorescences 5.1–7.5(–8.9) cm long; Titicaca basin (Puno, Peru; La Paz, Bolivia) P. incarum
Leaflets 0.4–0.6 cm wide; leaflet apices obtuse to emarginate; inflorescences 1.8–3.7 cm long; Depts. Cochabamba and north-western Potosi (Bolivia) P. subtusalbida
13 Leaflets 0.9–2.2 cm long; leaflet apices deeply emarginate without projection; Ecuador P. reticulata
Leaflets 0.9–3.3 cm long; leaflet apices round, obtuse, acute or emarginate with a mid-vein projection; Ecuador, Peru, Bolivia, Chile 14
14 Leaflet margins entire 15
Leaflet margins crenate 16
15 Leaflets 0.9–1.1 × 0.4–0.6 cm; upper leaflet surfaces glabrous to sparsely sericeous; lower leaflet surfaces sparsely to densely sericeous; inflorescences 0.9–1.1 cm long, with 1 flower P. rodolfovasquezii
Leaflets (1.3–)1.7–2.8 × 0.5–0.7 cm; upper leaflet surfaces sparsely strigose; lower leaflet surfaces densely strigose; inflorescences (1.9–)2.5–4.9(–5.6) cm long, with 3–6 flowers P. subsericans
16 Lower leaflet surfaces densely tomentose with a dense underlying layer of very short, white pannose hairs 17
Lower leaflet surfaces densely pilose, villous or tomentose without pannose hairs 18
17 Upper leaflet surfaces smooth to slightly rugose; lower leaflet surface hairs 0.6–0.8 mm long; 7–9 flowers per inflorescence; central Bolivia P. besseri
Upper leaflet surfaces strongly rugose; lower leaflet surface hairs 0.8–1.0 mm long; 4–5 flowers per inflorescence; south-western Peru and north-western Chile P. rugulosa
18 Upper leaflet surfaces sparsely to densely pilose; 3–5 flowers per inflorescence; 11–17 stamens per flower 19
Upper leaflet surfaces glabrous to sparsely villous; 5–13 flowers per inflorescence; 19–23 stamens per flower 20
19 Lower leaflet surfaces densely pilose, hairs 0.5–0.6 mm long P. flavipila
Lower leaflet surfaces densely villous, hairs 1.0–1.2 mm long P. pilosissima
20 Leaflet apices round to emarginate; upper leaflet surfaces sparsely villous; lower leaflet surfaces densely villous, hairs 0.9–11 mm long; inflorescences 2.0–4.0 cm long, with 5–7 flowers; south-central Peru P. acomayensis
Leaflet apices acute; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose, hairs 0.4–0.8 mm long; inflorescences (4.9–)5.5–7.0(–9.5) cm long, with 11–13 flowers; southern Peru and northern Bolivia P. triacontandra
21 Lateral leaflets 4–7 pairs 22
Lateral leaflets 2–3 pairs 38
22 Lower leaflet surfaces glabrous to puberulous; fruits with 2–3(–4) irregular and pronounced, thin wings P. neglecta
Lower leaflet surfaces sparsely or densely lanate, sericeous, villous or tomentose, hairs 0.3–2.3 mm long; fruits with variable numbers of flattened or long, hard spines 23
23 Leaflets 0.3–0.7 cm long; leaflet apices deeply emarginate; inflorescences 3.8–5.3 cm long, with 1–3 flowers P. microphylla
Leaflets 1.1–5.4 cm long; leaflet apices slightly emarginate to emarginate; inflorescences 2.4–36.0 cm long, with 4–83 flowers 24
24 Lower leaflet surfaces sparsely or densely sericeous 25
Lower leaflet surfaces densely lanate, villous or tomentose 31
25 Leaflet margin entire or serrate 26
Leaflet margin slightly crenate to crenate 28
26 Leaflets (0.8–)1.1–1.5 cm wide; lower leaflet surface hairs 1.3–1.7 mm long P. canoi
Leaflets 0.4–0.9 cm wide; lower leaflet surface hairs 0.2–0.9 mm long 27
27 Leaflets broadly obovate; upper leaflet surfaces glabrous with few hairs on the mid-vein P. loxensis
Leaflets narrowly elliptic to elliptic; upper leaflet surfaces glabrous to sparsely sericeous 28
28 Lateral leaflet 3–4 pairs 29
Lateral leaflet 4–7 pairs 30
29 Leaflet margins slightly crenate at the apex; inflorescences 3.9–6.6(–7.8) cm long, with 18–21 flowers; northern Peru P. albicans
Leaflet margins entire; inflorescences 13.0–17.9(–20.4) cm long, with 23–29 flowers; central Ecuador P. humboldtii
30 Leaflets 1.6–3.0 cm long; leaflet margins entire to slightly serrate; lower leaflet surfaces of mature plants with hairs 0.3–0.5 mm long; north-western Ecuador and southern Colombia P. ochreata
Leaflets (1.1–)1.4–1.6 cm long, leaflet margins crenate; lower leaflet surfaces of mature plants with hairs 0.3–0.4 mm long; north-eastern Ecuador P. pauta
31 Lower leaflet surfaces densely lanate or villous, the hairs 0.7–1.8 mm long 32
Lower leaflet surfaces densely tomentose, the hairs 0.3–1.5 mm long 35
32 Leaflet margin entire to slightly crenate; northern Ecuador P. longipilosa
Leaflet margins serrate; northern Colombia, Peru 33
33 Leaflets 0.4–0.8 cm wide, obovate; leaflet apices slightly emarginate; 7–15 flowers per inflorescence; north-western Colombia P. frontinensis
Leaflets 0.8–2.0 cm wide, elliptic; leaflet apices acute or obtuse; 16–83 flowers per inflorescence; Peru 34
34 Leaflets 1.1–2.0 cm wide; leaflet apices obtuse; lower leaflet surfaces densely villous; inflorescences (15.4–)21.7–28.2(–36.0) cm long, with 47–83 flowers P. multijuga
Leaflets 0.8–1.0(–1.2) cm wide; leaflet apices acute; lower leaflet surfaces densely lanate; inflorescences (7.6–)9.5–13.3(–17.3) cm long, with 16–35 flowers P. serrata
35 Leaflet apices moderately emarginate; upper leaflet surfaces sparsely tomentose; Bolivia and Argentina P. hieronymi
Leaflet apices deeply emarginate; upper leaflet surfaces glabrous; Colombia, Ecuador and Peru 36
36 Lateral leaflets (1–)2–3(–4) pairs; lower leaflet surface hairs 0.6–1.5 mm long; Ecuador P. reticulata
Lateral leaflets 3–5 pairs; lower leaflet surface hairs 0.3–0.9 mm long; Colombia and Peru 37
37 Leaflets 0.5–0.8 cm wide; lower leaflet surface hairs 0.3–0.6 mm long; inflorescences 2.4–6.7 cm long, with 4–12 flowers; northern Peru P. occidentalis
Leaflets 0.7–1.1 cm wide; lower leaflet surface hairs 0.7–0.9 mm long; inflorescences (6.0–)7.3–10.5(–12.3) cm long, with 11–19 flowers; north-eastern Colombia P. quadrijuga
38 Lower leaflet surfaces glabrous to sparsely hispid, puberulous, or pannose, the hairs < 0.2 mm long 39
Lower leaflet surfaces sparsely to densely lanate, sericeous, tomentose or villous, the hairs 0.3–2.5 mm long 42
39 Leaflets 0.5–0.8 cm wide; leaflet margins crenate, with 5–8 teeth per side; lower leaflet surfaces glabrous to sparsely villous; southern Peru P. pallidistigma
Leaflets 0.4–1.5 cm wide; leaflet margins serrate with 9–18 teeth per side; lower leaflet surfaces glabrous; Argentina and Bolivia 40
40 Leaflet margins with 12–18 teeth per side; leaflet apices acute; 14–27 flowers per inflorescence; Argentina and Bolivia P. neglecta
Leaflet margins with 9–13 teeth per side; leaflet apices obtuse to emarginate; 5–12 flowers per inflorescence 41
41 Leaflets elliptic, lower leaflet surfaces glabrous to sparsely hispid; fruits with 2–3 irregular and pronounced thin wings, glabrous; Argentina P. australis
Leaflets obovate, lower leaflet surfaces pannose; fruits with 2–4 wide flattened hard irregular ridges, sparsely tomentose; Argentina and Bolivia P. crista-galli
42 Lower leaflet surfaces densely lanate, the hairs 1.3–2.5 mm long 43
Lower leaflet surfaces sparsely to densely sericeous, tomentose or villous, the hairs 0.3–2.0 mm long 45
43 Leaflets elliptic; upper leaflet surfaces glabrous to sparsely lanate; lower leaflet surface hairs 1.5–2.5 mm long, yellowish; 13–16 flowers per inflorescence; Ecuador P. lanuginosa
Leaflets obovate to broadly obovate; upper leaflet surfaces sparsely lanate; lower leaflet surface hairs 1.3–1.5 mm long, whitish; 5–11 flowers per inflorescence; Peru and Bolivia 44
44 Leaflets (1.8–)2.2–2.7 × 0.9–1.4 cm; inflorescences (5.0–)6.1–4.9(–12.3) cm long; Bolivia P. lanata
Leaflets 1.6–2.6 × 0.6–1.1 cm; inflorescences 5.0–8.8 cm long; Peru P. sacra
45 Lower leaflet surfaces densely sericeous, the hairs 0.2–1.7 mm long 46
Lower leaflet surfaces sparsely to densely tomentose or villous, the hairs 0.4–2.0 mm long 52
46 Leaflets 0.8–1.3 × 0.2–0.7 cm; inflorescences 1.2–1.6(–3.5) cm long, with 3 flowers; southern Peru and Bolivia P. pepei
Leaflets 1.2–3.9 × 0.4–1.5 cm; inflorescences 3.3–20.4 cm long, with 5–29 flowers; Venezuela to Bolivia 47
47 Leaflets (2.4–)3.4–3.9 × (0.8–)1.1–1.5 cm; lower leaflet surface hairs 1.3–1.7 mm long, yellowish; central Peru to Bolivia P. canoi
Leaflets 1.2–2.8 × 0.4–1.0 cm; lower leaflet surface hairs 0.2–1.0 mm long, silky, whitish; Venezuela to central Peru 48
48 Lateral leaflets 3–5 pairs; lower leaflet surface hairs 0.2–0.6 mm long; Ecuador and north-western Peru 49
Lateral leaflets 2–3 pairs; lower leaflet surface hairs 0.6–1.0 mm long; Venezuela, Colombia, central Peru 51
49 Leaflet margins entire; inflorescences 13.0–17.9(–20.4) cm long, with 23–29 flowers P. humboldtii
Leaflet margins slightly crenate at the apex or serrate; inflorescences 3.5–12.2 cm long, with 9–27 flowers 50
50 Leaflets elliptic; leaflet margins slightly crenate at the apex; north-western Peru P. albicans
Leaflets broadly obovate; leaflet margins serrate; southern Ecuador P. loxensis
51 Leaflets (1.9–)2.4–2.6 × 0.5–0.7 cm; upper leaflet surface sparsely to dense sericeous; inflorescences 7.2–8.1 cm long; central Peru P. argentea
Leaflets 1.8–2.1 × 0.8–1.0 cm; upper leaflet surfaces glabrous; inflorescences 3.3–4.5 cm long; Venezuela and Colombia P. sericea
52 Leaflet margins serrate 53
Leaflet margins entire to crenate 55
53 Lateral leaflets 3–4(5) pairs; lower leaflet surface densely villous; Colombia P. frontinensis
Lateral leaflets 1–2 pairs; lower leaflet surfaces sparsely to densely tomentose; Ecuador, Peru and Bolivia 54
54 Leaflets (2.3–)3.1–3.9 × (0.7–)0.9–1.5 cm, apices round; inflorescences (4.2–)5.0–9.4(–11.7) cm long, with 7–21 flowers; Ecuador and Peru P. racemosa
Leaflets 0.9–1.6 × 0.4–0.6 cm, apices obtuse to emarginate; inflorescences 1.8–3.7 cm long, with 3–4 flowers; Bolivia P. subtusalbida
55 Leaflet apices acute, round, obtuse or emarginate; lower leaflet surfaces densely tomentose or villous with a dense underlying layer of very short pannose hairs; Peru and Bolivia 56
Leaflet apices moderately to deeply emarginate; lower leaflet surfaces densely tomentose without short pannose hairs; Ecuador to Argentina 59
56 Lower leaflet surface hairs 0.9–1.1 mm long; inflorescences 2.0–4.0 cm long; central Peru P. acomayensis
Lower leaflet surface hairs 0.4–0.9 mm long; inflorescences 3.6–10.0 cm long; southern Peru to Bolivia 57
57 Leaflets (2.0–)2.6–3.3 × 0.7–1.1 cm, narrowly elliptic; 11–13 flowers per inflorescence; Dptos. Puno (Peru) and La Paz (Bolivia) P. triacontandra
Leaflets 1.4–2.4 × 0.6–11 cm, narrowly obovate; 5–11 flowers per inflorescence; La Paz and Cochabamba (Bolivia) 58
58 Lateral leaflets 1–2(–3) pairs; stipular sheaths apically truncate; rachises and lower leaflet surfaces densely villous; Dpto. Cochabamba (Bolivia) P. besseri
Lateral leaflet 2–3 pairs; stipular sheaths apically acute; rachises and lower leaflet surfaces densely tomentose; Dpto. La Paz (Bolivia) P. pacensis
59 Leaflets (0.9–)1.3–1.6 × (0.4–)0.7–1.1 cm, broadly ovate; Ecuador P. simpsoniae
Leaflets 0.9–2.2 × 0.4–1.1 cm, elliptic to obovate; Colombia to Argentina 60
60 Leaflets narrowly obovate; upper leaflet surfaces sparsely tomentose; Bolivia and Argentina P. hieronymi
Leaflets narrowly elliptic to obovate; upper leaflet surfaces glabrous; Colombia to Peru 61
61 Lower leaflet surface hairs 0.3–0.6 mm long; Peru 62
Lower leaflet surface hairs 0.6–1.5 mm long; Colombia and Ecuador 63
62 Lateral leaflets 3–5 pairs; leaflets 1.1–1.9 cm wide; inflorescences 2.4–6.7 cm long P. occidentalis
Lateral leaflets 2–3 pairs; leaflets 1.6–2.1 cm wide; inflorescences 8.6–9.7 cm long P. weberbaueri
63 Lower leaflet surface hairs 0.7–0.9 mm long; inflorescences (6.0–)7.3–10.5(–12.3) cm long, with 11–19 flowers; north-eastern Colombia P. quadrijuga
Lower leaflet surface hairs 0.6–1.5 cm long; inflorescences (2.3–)4.3–13.8 cm long, with 5–9 flowers; Ecuador P. reticulata

Polylepis sect. Sericeaee T. Boza & M. Kessler,, sect. nov.

Diagnosis

Trees or shrubs; lower leaflet surfaces with sericeous, lanate or villous hairs; fruits with a variable number and placement of flattened, thin or short spines, densely sericeous or villous.

Type

Polylepis sericea Wedd.

Notes

The sectional epithet Sericeae is a plural adjective agreeing in gender with Polylepis. This section, already defined as a group by Simpson (1986), includes species that usually have sericeous hairs on the lower leaflet surfaces and/or stipule sheaths and whose leaves usually contain many pairs of leaflets. Furthermore, fruits in this section are turbinate with a variable number of slender spines. However, not all species share these traits. For instance, P. frontinensis and P. multijuga have villous hairs on the lower leaflet surfaces, but P. frontinensis has sericeous hairs on the stipule sheaths and P. multijuga has many leaflets pairs (5–7). In the same way, P. lanuginosa and P. serrata have lanate hairs, but both have many lateral leaflets pairs. Polylepis multijuga, P. ochreata, P. pauta and P. serrata are the species with most leaflet pairs (4–7), whereas P. rodolfovasquezii just has one pair. Moreover, P. pepei and P. rodolfovasquezii have turbinate, but slightly twisted fruits with short spines. This variation may reflect that this section is likely not monophyletic, but rather has been proposed to represent a basal grade within the genus (Schmidt-Lebuhn et al. 2006a).

The majority of species in this section are morphologically clearly distinct. Probably the two most similar species are P. pepei and P. rodolfovasquezii, which only differ in a few, partly overlapping characters. They might be treated at subspecies level, but as detailed in the Introduction, we decided not to accept infraspecific taxa because of the difficulty of deciding at which level to discriminate between species- and subspecies-level differentiation. Table 4 provides an overview of the arrangement of the taxa by different authors.

Table 4.

Alignment of the species of the Polylepis sect. Sericeae according to Bitter (1911), Simpson (1979), Segovia et al. (2018) and the present study.

Bitter (1911) Simpson (1979) Segovia et al. (2018) This study
P. albicans P. sericea P. sericea P. albicans
P. ochreata P. ochreata
P. hypargyrea P. sericea
P. sericea
P. argentea
P. frontinensis
P. humboldtii
P. loxensis
P. canoi P. canoi
P. coriacea P. lanuginosa P. lanuginosa P. lanuginosa
P. lanuginosa
P. lehmannii
P. multijuga P. multijuga P. multijuga P. multijuga
P. annulatipilosa P. pauta P. pauta P. pauta
P. pauta
P. stuebelii
P. longipilosa
P. serrata P. serrata
P. pepei P. pepei P. pepei
P. rodolfo-vasquezii P. rodolfo-vasquezii

Within section Sericeae, we recognize four subsections, based on their morphological distinctness, as follows: subsection Lanuginosae (two species) with lanate or villous lower leaflet surfaces and densely villous fruits; subsection Pauta (three species) with 4–6 lateral leaflet pairs and lanate or sericeous lower leaflet surfaces; subsection Sericeae (eight species) with sericeous lower leaflet surfaces (except P. frontinensis) and fruits with flattened spines; and subsection Pepea (two species) with 1–2 lateral leaflet pairs, emarginate leaflet apices and densely sericeous, slightly twisted fruits with short spines.

Climatic niches in Polylepis sect. Sericeae

Many species of this section differ markedly in their climatic niches (Figs 12 and 13). For example, Polylepis albicans and P. sericea from subsect. Sericeae and P. pepei and P. rodolfovasquezii from subsect. Pepea grow under the coldest conditions (about 5.5 °C Mean Annual Temperature – MAT), whereas other species, such P. multijuga (10.0 °C) from subsect. Lanuginosae and P. serrata (9.6 °C) from subsect. Pauta, grow under noticeably higher temperatures. These differences of 4–5 °C correspond to 800–1000 m in elevation. Regarding Mean Annual Precipitation (MAP), P. frontinensis grows under the most humid conditions (mean of 2048 mm MAP), followed by P. canoi (1572 mm). In contrast, P. albicans and P. humboldtii on average receive only 744 mm per year, whereas P. lanuginosa (847 mm), P. pauta (941 mm) and P. multijuga (986 mm) also grow in relatively dry conditions.

Figure 12. 

Box plots showing the climatic niches of the species of the subsections Lanuginosae, Pauta and Pepea in relation to Mean Annual Temperature (MAT) (A) and Mean Annual Precipitation (MAP) (B). The ends of each box represent the upper and lower quartiles and the median is indicated with a bold line inside the box; the whisker lines extend to the highest and lowest observations, except when observations are higher or lower than the interquartile range (i.e. outliers), in which case they are indicated by a dot. Box plots that share the same lowercase letters within each subsection are not significantly different at p = 0.05. Vertical lines represent subsectional divisions.

Focussing on the individual subsections, the two species in subsect. Lanuginosae show minor ecological differences and replace each other geographically. In subsect. Pauta, P. longipilosa and P. pauta from northern Ecuador have quite similar climatic niches and replace each other geographically, whereas P. serrata from Peru grows under substantially higher temperatures and higher precipitation. The two very similar species of subsect. Pepea have identical niches and complementary geographical distributions. These species clearly form a vicariant species pair, suggesting allopatric speciation after geographical isolation. Finally, in subsection Sericeae, there are major differences among almost all species, with only P. albicans and P. humboldtii having similar climatic niches, but these are geographically well separated. Indeed, all species of this subsection are geographical vicariants, except for P. argentea and P. canoi, which broadly overlap geographically, but have quite different niches, with P. argentea growing under colder and drier and P. canoi under warmer and more humid conditions. These marked ecological differences between species show that they are evolutionarily and ecologically independent lineages and support their treatment as separate species.

Figure 13. 

Box plots showing the climatic niches of the species of subsection Sericeae in relation to MAT (A) and MAP (B). See Fig. 12 for details on data presentation.

Lanuginosae T.Boza & M.Kessler, subsect. nov.

Diagnosis

Trees; 3–6(–7) lateral leaflet pairs; lower leaflet surfaces lanate or villous; fruits with flattened spines, densely villous.

Type

Polylepis lanuginosa Kunth.

Notes

The subsectional epithet Lanuginosae is a plural adjective agreeing in gender with Polylepis.

Polylepis lanuginosa Kunth, Nov. Gen. Sp. (quarto ed.) 6: 228. 1824.

Figs 14, 15

Polylepis lehmannii Hieron. Bot. Jahrb. Syst.20: Beibl. 49: 29. 1895. Type. Ecuador. Azuay: west of Cuenca, Lehmann 6487 (holotype: B destroyed; isotype: F!).

Polylepis coriacea Bitter Bot. Jahrb. Syst. 45: 603. 1911. Type. Ecuador. Chimborazo: Valley of Pangor Spruce s.n (holotype: W, photos at F!, MO!, US!).

Type

Ecuador. Chimborazo: near Calpi “ad radicem montis Chimborazo”, June 1903, Humboldt & Bondpland 2191 (holotype: P!; isotypes: P!, photo at F!).

Figure 14. 

Polylepis lanuginosa Kunth A flowering branch B upper leaf surface C leaves D lower leaf surface E habit. Scale bars: 2 cm (A, C); 1 cm (B, D). Photographs by T.E. Boza E.

Description

Trees 3–8 m tall. Leaves slightly congested at the branch tips, imparipinnate with 2–3 pairs of lateral leaflets, obtrullate in outline, (4.5–)5.2–7.7 × 3.4–4.5 cm; rachises densely villous, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.7–2.8 × 0.7–1.4 cm; margin crenate with 8–9 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous or sparsely lanate; lower leaflet surfaces densely lanate with yellowish hairs 1.5–2.5 mm long. Inflorescences branched at the base or simple, pendant, (4.3–)6.2–9.5(–13.0) cm long, bearing 13–16 flowers; floral bracts 3.8–5.5 mm long, narrowly triangular, densely lanate on the outer surface; rachises villous. Flowers 5.8–7.5 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 13–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.9–2.3 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 4.4–6.0 × 6.1–7.4(–9.8) mm including spines. Diploid.

Figure 15. 

Polylepis lanuginosa Kunth A flowering branch B upper leaf surface C lower leaf surface D fruit E stipular sheaths (A Romoleroux 584 B Laegaard 53932 C Harling 22858 D, E Laegaard 55036). Scale bars: 5 cm (A); 4 cm (B, C); 1 cm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis lanuginosa is endemic to central and southern Ecuador (Azuay, Bolívar, Cañar and Chimborazo) (Fig. 24). It occurs in Andean forests at 2300–4200 m elevation. It has been recorded within Cajas National Park where it forms patches mainly on hillsides. Among the Polylepis species that co-occur in this area (P. incana, P. lanuginosa, P. reticulata, P. simpsoniae and introduced P. racemosa), P. lanuginosa occupies the warmest habitats, has the largest foliar area (17.3 cm2) and the highest leaf mass (> 200 mg). In its forest habitat, P. lanuginosa is co-dominant with other tree species, such as Oreopanax andreanus, Weinmannia fagaroides and Sessea corymbosa, which often exceed it in height (Montalvo et al. 2018).

Conservation status

Based on 17 collecting localities, the estimated EOO is 6,910 km2 and the occupied habitat or AOO is 96 km2. It is protected within Cajas National Park. The species was categorized as VU B1+2c by Oldfield et al. (1998) and as VU B1ab(iii) by León-Yánez et al. (2011). Small patches of Polylepis lanuginosa growing close to roads are especially exposed to erosion and logging. We assess P. lanuginosa as Endangered (B1a+B2a, C1).

Notes

Polylepis lanuginosa is most similar to P. multijuga, with which it shares the leaflet shape and hair density. However, it differs from it and all other members of the genus by its branched inflorescences. Further, P. lanuginosa has crenate leaflets 1.7–2.8 cm long, whereas P. multijuga has serrate leaflets 2.9–5.4 cm long. In P. lanuginosa, the hairs on the lower leaflet surfaces are densely lanate, whereas in P. multijuga, they are densely villous. Polylepis lanuginosa is also morphologically similar to P. canoi, but differs in its elliptic and shorter (1.7–2.8 cm long) leaflets (versus leaflets obovate and 2.4–3.9 cm long). Additionally, P. lanuginosa has shorter styles (1.9–2.3 mm long) than P. canoi (2.4–3.8 mm long).

Specimens examined

Ecuador. — Azuay: Chaucha, Angas on western slope of western cordillera (due west of Cuenca), 02°55'S, 079°25'W, 3400 m, 05 January 1981, Balslev 1507 (AAU!, NY, QCA!, S); Angas “Parroquia chaucha” colecciones en margenes de Río Angas, 3400 m, 02 August 1983, Jaramillo 5464 (AAU!, NY, QCA!); 5468 (AAU!); 5478 (AAU!, MO!, NY, QCA!); Cuenca, Area Nacional de Recreación Cajas, collection made along Río Patul from the Comunidad Baute/Laguna Patul (watershed of Río Patul), 02°33'S, 079°21'W, 3500–4200 m, 05 February 2001, Clark 6227 (QCA!, QCNE, US!); Molleturo, on the road from Las Cajas National Park to Molleturo, about 10 km from Molleturo, 02°50'S, 079°20'W, 3400 m, 19 September 1983, Brandbyge 42264 (AAU!, MO!, QCA!); Cuenca-Molleturo road ca. 11 km W of pass in Las Cajas, 02°48'S, 079°18'W, 3350 m, 01 May 1992, Lægaard 102637 (AAU!, QCA!); Páramo de Cajas, W of Cuenca, along new road, ca. 14 km W of pass, 02°48'S, 079°17'W, 3450 m, 31 March 1985, Lægaard 53932 (AAU!); Páramo de Cajas, W of Cuenca, along new road, ca. 20 km W of pass, 02°48'S, 079°17'W, 2900 m, 31 March 1985, Lægaard 53934 (AAU!, MO!, QCNE); Páramo de las Cajas, W of pass, 02°46'S, 079°15'W, 2500 m, 26 August 1985, Lægaard 55036 (AAU!, MO!, QCA!); carretero Cuenca-Molleturo-Naranjal, 4.2 km de Molleturo, desvío a Río Blanco 16.4 km, 02°48'40"S, 079°23'07"W, 3630 m, 15 January 2003, Ulloa 1203 (HA, MO!, US!); Sayausi, Area Recreacional Las Cajas, 02°49'S, 079°07'W, 3740–4070 m, Romoleroux 1192 (AAU!); Zhud, at Panamericana, app. 3 km S of Zhud, 02°29'S, 079°00'W, 2800 m, 02 May 1992, Lægaard 102697 (AAU!, QCA!); límite del parque nacional, 3359 m, 20 April 2012, Barba BOP236 (QCA!); Río Blanco, Curiquinga, 3645 m, 05 May 2001, Calle 1 (QCA!); Cuenca-Molleturo road, 49 km NW of Cuenca, 26 July 1982, Clemants 2184 (AAU!, NY, QCA!); El Chorro ca. 6 km above Molleturo on road to Cuenca, 2800–2900 m, 07 March 1985, Harling 22858 (AAU!, GB, MO!, QCA!); Molleturo, 2600–2700 m, 31 October 1988, Harling 25539 (GB, MO!); Descente occidentale du páramo de Cajas vers Molleturo, 3350 m, 14 April 1988, Huttel 1021 (QCA!); Vallée du río Angas, à 1 Km au-dessus du hameau d’Angas, zone trés humide, 3300 m, 10 May 1988, Huttel 1112 (QCA!); Vertiente del Pacífico, 3200 m, 07 July 1995, León 3601 (QCA!); Área recreacional Cajas, 3470 m, 21 September 2000, Lizarzaburu 25 (QCA!); 3500 m, Romoleroux 408 (NY); Parque Nacional Cajas, carretera Soldados, 3260 m, 04 April 2007, Romoleroux 4461 (QCA!); 3040 m, 04 April 2007, Romoleroux 4466 (QCA!); Vía Soldados Angas, al frente del caserío Angas, 3321 m, 19 August 2008, Romoleroux 5030 (QCA!); Carretera Soldados-Angas, 3040 m, 04 April 2007, Romoleroux GPI4466 (QCA!); Cajas, found along path from Cochapamba to Molleturo, 3500–3600 m, 22 July 1999, Smeets 559 (QCA!); 2670–3275 m, Steyermark 52599 (F!); 3160 m, Valencia 458 (QCA!). — Bolívar: carretera Guaranda-Santiago-Totoras, 3000–3150 m, 21 February 1987, Romoleroux 269 (AAU!, QCA!). Cañar: Molleturo, along Páramo road to Manu W of Cañar, W of pass, 02°33'S, 079°02'W, 3300–3700 m, 20 June 1988, Lægaard 71563, 71565, 71569 (AAU!, QCNE); Molleturo, Páramo de Cajas, W of Cuenca, aong new road, ca. 11 km W of pass, 02°48'S, 079°17'W, 3200 m, 30 March 1985, Lægaard 53911 (AAU!, MO!, QCA!); Zhud, along Panamericana, 4 km S of Zhud, 02°28'S, 079°00'W, 3000 m, 26 August 1985, Lægaard 55030 (AAU!, MO!); along a paved road to Carshao, ca. 15 km off the Panamerican highway, 02°29'S, 079°00'W, 3180 m, 10 June 1999, Sklenar 7115 (AAU!); carretera entre Dacur y Gun, 2250 m, 08 October 1999, Bonifaz 3974 (QCA!); North rim of the valley of the río Cañar, between Tambo and Suscal, 3000 m, 23 April 1944, Camp E-2773 (F!, NY, VEN); colecciones entre Zhud, Joyagshi, 3500 m, 31 December 2007, Jaramillo 26120 (QCA!); 3300–3700 m, Romoleroux 1563 (QCA!); 3270 m, Romoleroux 384 (QCA!); 3100 m, Romoleroux 387 (NY, QCA!); carretera entre Zhud y El Tumbo, 3011 m, 06 December 2007, Romoleroux 4681 (QCA!); Oeste de Cañar, Km 10.5, Cerro Caucay, 3450 m, 27 April 1988, Romoleroux 588 (AAU!, MO!); Rose 2389 (NY). Chimborazo: Columbe, road Pallantanga-Riobamba, 01°55'S, 078°50'W, 2400–2900 m, 01 April 1993, Romoleroux 1565 (AAU!, QCA!); Juan de Velasco, Pangor-Tepeyac, 01°48'S, 078°52'W, 3200 m, 09 February 1983, Brandbyge 42059 (AAU!, MO!);, 3300 m, 03 May 1983, Brandbyge 42153 (AAU!, MO!, QCA!); Colta (Cajabamba)–Pallatanga, km 27, 01°50'S, 078°53'W, 2880 m, 21 May 1990, Jørgensen 91822 (AAU!); Km 64–68 on road Cumandá-Cajabamba, at Río Pangor, 01°55'S, 078°54'W, 2750–2800 m, 08 April 1985, Lægaard 54125 (AAU!, MO!, QCA!), 54128 (AAU!, QCA!); road Pallatanga–Cajabamba, 32 km from Pallatanga, 01°51'S, 078°53'W, 3000 m, 28 August 1976, Øllgaard 8959 (AAU!, MO!, NY, S). Penipe, Parroquia Puela, Palictahua, 01°31'05"S, 078°29'43"W, 2600 m, 20 January 1997, Estudiantes ESPOCH 701 (CHEP); Colta, Pangor, puente del Río Agua Dulce, 3000 m, 31 January 2007, Caranqui 1659 (QCA!); Colta. Pangor, Achín alto, 3140 m, 21 May 2013, Caranqui 2290 (QCA!); Comunidad de Tauris, Zona Zagin, 3700–3900 m, 03 September 2009, Cárate 1202 (QCA!); Comunidad de Ambrosio Lazo, Quebrada de Cumbo, 3374 m, 07 June 2009, Cárate 623, 624 (QCA!); Páramo cerca de la comunidad Yerba Buena, Cantón Pallatanga, 3374 m, 19 July 2012, Peyre 315 (QCA!); 2800–3200 m, Romoleroux 373 (NY, QCA!); Vía Cajabamba–Pallatanga (km 24 desde la Y), entrada a Pangar, 3298 m, 27 December 2011, Romoleroux 5696 (QCA!); Vía Cajabamba-Palatanga (km 24 desde la Y), entrada al Pangar, 3298 m, 27 December 2011, Romoleroux 5697 (QCA!); Carretera Alausi-Cañar, km 16, localidad Achupallas, 3400 m, 26 April 1988, Romoleroux 574 (AAU!, QCA!); Cañar, 2 km al sur de Zhud, 2850 m, 27 April 1988, Romoleroux 584 (AAU!, QCA!); 3250 m, Romoleroux 591 (QCA!), W Andes of Cuenca, Lehmann 6487 (F!).

Polylepis multijuga Pilg., Bot. Jahrb. Syst. 37: 536. 1906.

Figs 16, 17

Type

Peru. Cajamarca: at Chugur near Hualgayoc, 2700–3000 m, May 1904, Weberbauer 4098 (holotype: G!; isotypes: MOL!; photos at F!, MO!).

Figure 16. 

Polylepis multijuga Pilg A flowering branch B flowers C stipular sheaths D upper leaf surface E lower leaf surface F bark G flowers H habit (A–H Boza & Urquiaga 3008). Scale bars: 4 cm (A); 1 cm (B); 2 mm (C); 2 cm (D, E); 8 mm (G). Photographs by E.G. Urquiaga F.

Description

Trees 5–15 m tall. Leaves slightly congested at the branch tips, imparipinnate with 5–7 pairs of lateral leaflets, obtrullate in outline, (11.0–)14.6–19.5 × 6.2–9.1(–10.7) cm; rachises densely lanate, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 2.9–3.6(–5.4) × 1.1–2.0 cm; margin serrate with 6–10 teeth, apically obtuse, basally unequally cordate; upper leaflet surfaces glabrous or sparsely villous; lower leaflet surfaces densely villous with whitish hairs 0.9–2.3 mm long. Inflorescences pendant, (15.4–)21.7–28.2(–36.0) cm long, bearing 47–83 flowers; floral bracts 7.6–9.7 mm long, narrowly triangular, densely villous on the outer surface; rachises villous. Flowers 6.4–7.5 mm diam.; sepals 4, ovate, green, densely lanate outside; stamens 7–13, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.9–3.8 mm long. Fruits turbinate, with variable numbers and placement of irregular spines, densely villous; 4.5–9.6 × 6.0–10.1 mm including spines. Diploid.

Figure 17. 

Polylepis multijuga Pilg A flowering branch B upper leaf surface C lower leaf surface D fruit. (A, B Weigend 98/330 C Castillo 786 D Ferreyra 20908). Scale bars: 6 cm (A); 2 cm (B, C); 8 mm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis multijuga is restricted to northern Peru (Fig. 24). It grows mainly in the upper montane forest at 2700–3750 m elevation, usually in mixed forest with species of Cyathea, Escallonia, Gynoxys and Weinmannia (Weberbauer 1911). Its branches are often covered with epiphytes (Simpson 1979).

Conservation status

Based on 22 localities, the EOO for Polylepis multijuga is estimated at 17,200 km2 and the AOO at 116 km2. The species was categorized as VU (B1+2c, D2) in the World List of Threatened Trees (Oldfield et al. 1998). Later, based on its fragmented habitat affected by human disturbance, it was listed as EN (B1ab(iii)) in the Red List of Peru (SERFOR 2006; León-Yánez et al. 2011). It does not occur in any protected area and mining and forestry activities have led to its disappearance at several former locations (Guerrero 2009). Deforestation of remnant P. multijuga patches and extended reforestation with Pinus, which dries and acidifies the soils, are further reducing populations. The small, fragmented, and declining populations of this species are characterized by low genetic diversity (Quinteros-Casaverde et al. 2012). Based on its fragmented and degraded distribution, continuing habitat loss, and lack of habitat protection, we assess P. multijuga as Critically Endangered (A1, B1a+B2a, C1).

Notes

Polylepis multijuga is similar to P. canoi but has 5–7 pairs of elliptic leaflets, whereas the latter has 2–4 pairs of obovate leaflets. Polylepis multijuga also has longer inflorescences (15.4–36.0 cm) with 47–83 flowers (P. canoi 8.2–14.5 cm, 12–26 flowers). Polylepis multijuga is also similar to P. ochreata, but differs by having larger and broader leaflets (2.9–5.4 × 1.1–2.0 cm versus 1.6–3.0 × 0.5–0.7 cm) and densely villous lower leaflet surfaces (densely sericeous in P. ochreata). Polylepis ochreata also has shorter inflorescenses (8.1–17.4 cm) with fewer flowers (21–49).

Specimens examined

Peru. Amazonas: Chachapoyas, Dist. Leymebamba, surroundings of La Esperanza, 06°49'04"S, 077°43'01"W, 3200–3300 m, 27 June 2010, Glenn 411 (CAS, COL!, F!, K, MO!, P!); Dist. Leymebamba. Río El Jardín, 06°55'52"S, 077°43'09"W, 3370 m, 30 June 2009, Gruhn 173 (MO!); Dist. Leymebamba, a 2 Km de la Laguna de Los Cóndores, ruta hacia Leymebamba, 2700–2950 m, 18 August 1998, Quipuscoa 1329 (MO!); Quintecocha. Dist. Leymebamba, vicinity of guard cabin at Quintecocha, 06°51'33"S, 077°42'15"W, 3134 m, 12 July 2008, Rothrock 239 (BRIT, MO!); Balsas, Chuquillurco, ruta a Calla Calla, 3400 m, 06 October 2001, Sánchez 11018 (MO!); Chachapoyas-Cajamarca road, jalca de Calla-Calla, 30–37 km from Leimebamba Natural grassland, ‘Jalca’, and ‘ceja de selva’ just leaving the pass entering the Marañon valley, 06°50'S, 077°50'W, 3500–3600 m, 04 September 1983, Smith 5037 (MO!, USM!); Leimebamba, Oseres, 06°58'05"S, 077°39'57"W, 2542 m, 22 May 2015, Vega 257 (HAO, MO!); road Balsas to Chachapoyas, upper eastern Calla-calla slopes descending from pass, 3000–3300 m, 02 June 1998, Weigend 98/330 (USM!). Luya, Distr. Conila-Cohechan, 06°16'25"S, 078°00'10"W, 3050 m, 23 August 2012, Bussmann 17289 (MO!); Colcamar, 3200–3300 m, 24–26 June 1948, Pennell 15632 (USM!). Cajamarca: Chota, Bosque de Pagaibamba (Ocshawilca), al oeste del Chorroblanco, entre Huambos y Querocoto, 2500 m, 18 October 1987, Sánchez 4588 (F!); Paccha, al O de Chadin, 3650 m, 22 July 1993, Sánchez 6586 (F!). Cutervo, Gruta de San Andres, 2200 m, 15 July 1990, Llatas 2749 (F!, MO!). Hualgayoc, Dist. de Chugur, 06°43'08"S, 078°42'58"W, 3222–3568 m, 12 August 2009, Castillo 786 (USM!); Hacienda Taulis, 13 km beyond Palmito junction towards La Playa, 2900 m, 02 September 1964, Hutchison 6463 (MO!, USM!); Chugur, sobre la ruta de Perlamayo, 2950–3000 m, 20 March 1988, Sánchez 4681 (AAU!, F!). San Miguel, El Prado, Hacienda Taulis, 06°59'02"S, 078°58'21"W, 3398 m, 01 June 2015, Boza 3029; 3070; 3071; 3072; 3073; 3074; 3075; 3076; 3077; 3078; 3079; 3080 (USM!, Z!); Quishuarpampa (Agua Blanca), 2900 m, 04 July 1986, Mostacero 1201 (F!, MO!); Quishuarpampa (El Tingo–Jalca de las Estacas), 07°21'00"S, 077°50'00"W, 2950 m, 12 May 1977, Sagástegui 8833 (MO!); Millán (El Tingo–Taulis), 3000 m, 20 June 1980, Sagástegui 9536 (F!, MO!, USM!); Sobre el desvio a Tongot, entre Quilcate bajo y Catilluc, 3050 m, 13 September 1991, Sánchez 5762 (MO!). Santa Cruz, Distr. Pulán, parte baja de la Quebrada Cocan, ladera Oeste, 3280 m, 02 November 2001, Sánchez 11112 (MO!); Dist. Pulan, La Palma, 2800 m, 12 February 2007, Santa 927 (USM!); ad Chugur versus Hualgayoc, 2700–2900 m, 1901–1929, Weberbauer 4098 (G, MO!). La Libertad: Bolivar, District Uchumarca, Páramo in surroundings of Vira Vira/Lagunas La Quinua, 07°00'12"S, 077°45'07"W, 3670 m, 17 May 2011, Bussmann 16931 (MO!). Huicungo, Dist. Uchumarca, 06°59'30"S, 077°43'07"W, 3140 m, 02 November 2012, Paniagua 8642 (MO!). Lambayeque: Ferrenafe, Dos Puentes, arriba de Incahuasi, 2900–3000 m, 09 July 1987, Ferreyra 20908 (USM!); road Incahuasi to Sinchihual and Tungula, 06°12'07"S, 079°17'57"W, 2897 m, 24 November 2014, Weigend 9660 (USM!).

Pauta T.Boza & M.Kessler, sect. nov.

Diagnosis

Trees; 4–6 lateral leaflet pairs; lowers leaflet surfaces lanate or sericeous; fruits with flattened or thin spines, densely villous.

Type

Polylepis pauta Hieron.

Note

The subsectional epithet Pauta is a noun in apposition ['Nomen vernaculum: Pauta'; fide: Hieron., Bot. Jahrb. Syst. 21(3): 314. 1895].

Polylepis longipilosa T.Boza, K.Romoleroux & M.Kessler, Phytoxa 454(2): 116. 2020

Figs 18, 19

Type

Ecuador. Carchi: Cantón Montúfar, Loma El Corazón (Bretaña), al sureste de Huaca, al este de la Colonia Huaqueña, Río Minas, 00°35'N, 077°42'W, 3200–3500 m, 9 Apr 1989, Tipaz 35 (holotype: QCA!; isotypes: AAU!, MO!).

Figure 18. 

Polylepis longipilosa T.Boza, K.Romoleroux & M.Kessler. Isotype: Tipaz 35 (AAU).

Description

Trees 5–10 m tall. Leaves strongly congested at the branch tips, imparipinnate with (4–)5–6 pairs of the lateral leaflets, obtrullate in outline, (3.8–)4.3–7.3 × 2.4–4.5 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight whitish to yellowish hairs; stipular sheaths apically truncate, densely sericeous in the upper surface; leaflets narrowly to ovate in outline, second pair from the terminal leaflet the largest, one of this pair 1.4–2.2 × 0.4–0.5 cm; margins entire to slightly crenate with 6–7 teeth, apically slightly emarginate seemingly acute by the prolongation of hairs, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely lanate with whitish silky hairs 1.1–1.6 mm long. Inflorescences pendant, (6.8–)11.1–16.6 cm long, bearing 19–29 flowers; floral bracts 6.1–9.4 mm long, narrowly triangular, glabrous on the outer surface; rachises densely sericeous. Flowers 4.8–5.5 mm diam.; sepals 4, ovate, green, glabrous outside; stamens 8–10, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.6–2.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 3.9–6.7 × 4.3–7.5 mm including spines. Diploid.

Figure 19. 

Polylepis longipilosa T.Boza, K.Romoleroux & M.Kessler A Flowering branch B young leaves C stipular sheaths D upper leaf surface E lower leaf surface (A Ramsay 911 B Hutel 1390 C Laegaard 54965 D, E Salgado 239a). Scale bars: 6 cm (A); 3 cm (B, D, E). Photographs by E. G. Urquiaga F.

Distribution, habitat and ecology

Polylepis longipilosa is restricted to north-western Ecuador (Carchi) (Fig. 24). It is highly likely that the species also occurs in adjacent Colombia. It grows in humid páramo habitats at 3200–3900 m elevation where it often co-occurs with P. ochreata, with which it hybridizes (Romoleroux 1996). It grows in mixed forest with Espeletia pycnophylla, Weinmannia sp. and Oreopanax sp. (Boada et al. 2008).

Conservation status

The EOO for Polylepis longipilosa is estimated as 17,689 km2, the AOO is assessed at 60 km2 and it is known from eight locations. It occurs in Reserva Ecológica El Angel. However, the Andean Forest and páramos at Carchi have, in recent years, come under increasing threat from timber cutting and forest burning and advancement of the agricultural frontier, which has contributed to the fragmentation and destruction of high Andean ecosystems (Boada et al. 2008). Based on its degraded and fragmented distribution, we assess P. longipilosa as Critically Endangered (A2a, B1a+B2a, C1+C2a).

Notes

The populations of Polylepis from Carchi on the southern slopes of Volcán Chiles and on the road between Maldonado and Tulcán have previously been identified either as P. ochreata (Simpson 1979; Romoleroux 1996, as P. sericea) or P. pauta (Romoleroux 1996). Here, we treat it as a distinct species which is morphologically closest to P. ochreata and P. pauta. The most obvious differences between P. longipilosa and these species are its longer (1.1–1.6 mm), densely lanate hairs compared to the shorter (0.3–0.5 mm), densely sericeous hairs of P. ochreata and relatively short (0.4–0.9 mm), sparsely sericeous hairs of P. pauta; the hairs of P. longipilosa are concentrated on the leaflet veins (as is also the case in P. pauta), whereas in P. ochreata, the hairs are generally evenly distributed. Polylepis longipilosa also differs from the other two species by the leaflet apex, with P. longipilosa having acute or rarely emarginate leaflet apices, whereas P. ochreata and P. pauta have always emarginate leaflet apices. Additionally, P. longipilosa has shorter styles (1.6–2.0 mm), whereas P. ochreata and P. pauta have styles 2.1–2.6 mm and 2.2–3.0 mm long, respectively. Romoleroux (1996) reported hybrids between P. longipilosa and P. ochreata (as P. sericea).

There are three distinctive collections of the P. pauta/sericea complexes that Boza Espinoza et al. (2020a) were unable to assign to species: Loja, Cerro Chinchilla, J. Jaramillo 7312B, AAU!, QCA!; Pichincha, Laguna Mojanda, Brandbyge 42200, AAU!, MO!, NY, QCA! and Molau 2294, AAU!, GB, QCA!. These collections resemble P. longipilosa, but have different leaflet shape (obovate vs. ovate) with serrate margins (vs. entire to slightly crenate), longer lower leaflet surface hairs (1.5–1.8 mm vs. 1.1–1.6 mm) and longer styles (2.7–3.0 mm vs. 1.6–2.0 mm). Despite targeted fieldwork at both collecting localities, we have been unable to study this form in the field. The specimens at Mojanda were collected in a well-known hybrid zone and although they are not simply intermediate between the potential parent species (P. incana, P. ochreata, P. pauta) so that they cannot simply be interpreted as hybrids, it is possible that some unique gene combinations in hybrids might lead to morphotypes that fall outside of the morphological range of the parent taxa. In Loja, the situation is somewhat different, because the only species present there is P. loxensis, so that a hybrid origin is less likely, although in a wind-pollinated genus, such as Polylepis, pollen dispersal might conceivably take place over long distances. Should these collections represent one or even two separate species, then, on present knowledge, they would be very rare or even on the verge of extinction.

Specimens examined

Ecuador. Carchi: Tulcán, carretera Túlcan-Tufiño-Maldonado-Chical col. en km 12 de Tufiño, cerca de las lagunas, 00°48'N, 077°55'W, 3900 m, 23 April 1993, Freire & Andersen 2547 (AAU!); road Tulcán-Maldonado, near Volcán Chiles, 00°48'N, 077°56'W, 3850–4000 m, 16 August 1985, Laegaard 54965 (AAU!, MO!, QCA!), 54967A, 54967B, 54967C (AAU!), 54967D, 54967E, 54967F (AAU!, QCA!); along the road from Tulcán to Volcán Chiles, 3900 m, 6 October1995, Sklenár & Kosteckova 1412A (QCA!); camino Tufiño, sitio Agua Hediondas, en la base del Volcán Chiles, límite con Colombia, 00°48'N, 077°54'W, 3500 m, 8 November 1993, Palacios 11847 (AAU!, MO!, QCNE); carretera entre Tulcán y Maldonado, faldas del Volcán Chiles, punto más alto del cruce de carretera, 00°45'N, 077°59'W, 3800 m, 19 May 1991, Palacios & Rubio 7349 (AAU!, MO!); southern slopes of Volcan Chiles, 00°49'N, 077°57'W, 3600 m, Ramsay 911 (QCA!, QCNE); route de Tufiño a Maldonado, 10 km après Tufiño, zone très humide, 3850 m, 06 July 1988, Huttel 1390 (QCA!); carretera San Gabriel-Shután alto, 3500 m, 25 March 1989, Jaramillo-Asanza 10862 (QCA!); comuna La Esperanza, páramo de El Artezón, sector Monte Redondo, 3789 m, 18 September 2007, Salgado 220B, 239A (QCA!).

Polylepis pauta Hieron., Bot. Jahrb. Syst. 21: 313. 1895.

Figs 20, 21

Polylepis annulatipilosa Bitter, Bot. Jahrb. Syst. 45: 596. 1911. Type. Ecuador. Pichincha: Andes of Quito, Jameson 16 (lectotype, designated by Simpson 1979, pg. 27: W, isolectotypes: G, GH; photos at F!, MO!, US!).

Polylepis stuebelii Hieron., Bot. Jahrb. Syst. 21: 313. 1896. Type. Ecuador. Napo: E slope of Cerro Quilindaña near Bambasacha, 3700 m, Stübel 204 (holotype: B destroyed; photos at F!, MO!, NY!, US!).

Type

Ecuador. Pichincha: “Corredor Machai”, 3900 m, Oct 1871, Stübel 232a (holotype: B destroyed; photos at F!, GH!, MO!).

Figure 20. 

Polylepis pauta Hieron A Inflorescence B fruits C upper leaflet surface D flowers E flowers F lower leaflet surface G bark. Scale bars: 2 cm (A, C, F); 2 mm (B, D, E). Photographs A–C, F–G T. E. Boza E. D M. Kessler E E.G. Urquiaga F.

Description

Trees 2–12 m tall. Leaves strongly congested at the branch tips, imparipinnate with 4–5(–6) pairs of the lateral leaflets, obtrullate in outline, 3.2–4.9 × 2.2–3.0 cm; rachises sparsely sericeous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically acute with spurs, glabrous to sparsely sericeous (adult) or densely sericeous (juvenile) in the upper surface; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair (1.1–)1.4–1.6 × 0.5–0.6 cm; margin crenate with 4–6 teeth, subcoriaceous, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous or sparsely sericeous with few hairs on the mid-veins; lower leaflet surfaces sparsely sericeous with whitish hairs 0.4–0.9 mm long. Inflorescences pendant, (8.1–)12.6–14.3(–19.3) cm long, bearing 9–15(–21) flowers; floral bracts (9.1–)10.0–12.2 mm long, narrowly triangular, densely sericeous on the outer surface; rachises densely villous. Flowers 6.0–7.4(–9.2) mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 9–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.2–3.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; (2.6–)3.4–5.5 × 3.3–6.0(–8.2) mm including spines. Tetraploid, aneuploid; perhaps also diploid.

Figure 21. 

Polylepis pauta Hieron A flowering branch B upper leaf surface C lower leaf surface D fruit E young leaves (A Zambrano G147 B Kessler 2750 C Kessler 2753 D Laegaard 103115 E Romoleroux 654). Scale bars: 4 cm (A); 2 cm (B, C); 5 mm (D); 3 cm (E). Photographs by E. G. Urquiaga F.

Distribution, habitat and ecology

Polylepis pauta occurs in the north-eastern Cordillera Oriental of Ecuador (Fig. 24). It grows in high Andean Forest at 2600–4200 m elevation, often mixed with other tree species such as Gynoxys acostae, Solanum stenophyllum and Hesperomeles obtusifolia (Cierjacks et al. 2007b, 2008). Many populations are restricted to small, isolated forest patches, but in Napo, Ecuador, the species shows no evidence of genetic isolation by distance (Aragundi et al. 2011). Larger forest patches with broader elevational ranges have higher genetic diversity than forest patches on steeper slopes and at higher elevations, possibly due to increasing vegetative reproduction with elevation (Cierjacks et al. 2007a; Aragundi et al. 2011). In the same general region, Cierjacks et al. (2008) found a decrease of the number of inflorescences with elevation. Overall, reproductive success is low and decreases with elevation, being higher in the forest interior than outside and even higher when the litter layer is removed (Cierjacks et al. 2007b). Forests of P. pauta support a diverse bryophyte flora with numerous endemic species (Gradstein and León-Yañez 2018).

Conservation status

The EOO for Polylepis pauta is estimated as 1,590 km2, the AOO is assessed at 132 km2 and it occurs at 14 locations. Large populations occur within Cayambe-Coca National Park and Antisana Ecological Reserve, but there is genetic evidence for a loss of genetic diversity due to forest fragmentation (Aragundi et al. 2011). Moderate cattle grazing increases seedling abundance, presumably due to the removal of the litter layer (Cierjacks et al. 2008). We assess P. pauta as Vulnerable (A1, B1a+B2a, C1).

Notes

Simpson (1979) noticed that it is possible to morphologically differentiate various geographical populations within P. pauta as defined by her to include the populations here separated under P. longipilosa and P. serrata. Based on our fieldwork in Ecuador to clarify the taxonomic position of the ecologically well-studied populations to the east of Quito, we recognize two species based on their morphology, ecology and geographical distribution: the populations of the north-eastern Cordillera Oriental as P. pauta and the northern population as P. longipilosa (Boza Espinoza et al. 2020a). Polylepis pauta differs from P. longipilosa by having shorter leaflets (1.1–1.6 cm versus 1.4–2.2 cm in P. longipilosa) with crenate margins and emarginate apex (versus entire to slightly crenate margins and acute to rarely emarginate apex), shorter hairs (0.4–0.9 mm versus 1.1–1.6 mm) and fewer flowers per inflorescence (9–21 versus 19–29). Occasionally, specimens of P. pauta resemble those of P. ochreata in having the same number of lateral leaflets, but leaflet margins are crenate in P. pauta and entire to slightly serrate in P. ochreata.

An outstanding feature of P. pauta are the differences in leaflet number, shape and indument between young and adult plants. On young plants, leaves look very similar to those of P. longipilosa, whereas as the plants mature, the leaves become almost glabrous and have 4–5 lateral leaflet pairs.

Specimens examined

Ecuador. Cotopaxi: 2 km S of Paso de la Virgen on road Quito-Baeza, 00°20'S, 078°13'W, 3850–4000 m, 16 May 1984, Lægaard 52133 (AAU!, QCA!). Imbabura: González Suárez, Lagunas de Mojanda, Laguna Negra, 00°08'N, 078°15'W, 3700 m, 22 September 1990, Øllgaard 98194 (AAU!); vía hacia la laguna de Mojanda, 00°08'N, 078°15'W, 3500–3700 m, 02 November 1987, Romoleroux 475 (AAU!, QCA!). Otavalo, road from Otavalo to lagunas Mojanda, ca. 3 km before the lakes, 00°10'N, 078°17'W, 3500–3700 m, 23 October 1983, Balslev 4450 (AAU!, QCA!). Quiroga, Cotacachi, Reserva Ecológica Cotacachi-Cayapas, 00°18'N, 078°22'W, 3300–3350 m, 02 March 1992, Peñafiel 1091 (MO!). Tocachi, Laguna Grande de Mojanda, 15 km S of Otavalo, 00°08'N, 078°16'W, 3750 m, 14 May 1985, Eriksen 59359 (AAU!); 59374 (AAU!). Mojanda, Tomauco, 3309 m, 05 June 2008, Salgado 428 (QCA!); Mojanda, Tomauco, 3274 m, 05 June 2008, Salgado 458 (QCA!); Páramo de Mojanda, on the SW slope of the peak Nudo de Mojanda, 4130 m, 06 November 2007, Sklenar 10746 (QCA!). Napo: Oyacachi, 0°12'S, 78°8'W, 3680 m, 08 April 2012, Homeier 4948 (QCA!); N of Volcán Los Puntos, 00°12'S, 078°10'W, 4200 m, 27 July 1985, Lægaard 54756A (AAU!); N of Volcán Los Puntos, 00°12'S, 078°10'W, 3850–3900 m, 28 July 1985, Lægaard 54756B (AAU!); N of Volcán Los Puntos, 00°12'S, 078°10'W, 3850–3900 m, 28 July 1985, Lægaard 54756C (AAU!); 54756D (AAU!); 54756E (AAU!); 54756F (AAU!); 54761 (AAU!, MO!); Reserva Ecológica Oyacachi, 00°13'49"S, 078°08'44"W, 3915 m, 16 December 2008, Romoleroux 5346 (MO!, QCA!). Papallacta, Oyacachi, 0°18'6"S, 78°8'28"W, 3970 m, 10 June 2009, Homeier 4191 (QCA!); Páramo de Papallacta, 00°20'S, 078°10'W, 12 January 2015, Kessler s.n (Z!); Pifo-Papallacta, 3–5 km E of Paso de La Virgen, Páramo-swamp, 00°21'S, 078°11'W, 3700–3900 m, 09 June 1992, Lægaard 103115 (AAU!, GOET!, QCA!); 3 km E of Paso de la Virgen on road Pifo-Papallacta, 00°20'S, 078°11'W, 3950–4050 m, 02 June 1985, Lægaard 54442 (AAU!, QCA!); 54443 (AAU!); 54444 (AAU!, MO!); 54446 (AAU!); 54447 (AAU!, MO!, QCA!); 54448 (AAU!, MO!, QCA!); 54449 (AAU!, QCA!); 54450 (AAU!, MO!); 54451 (AAU!, MO!); 54452 (AAU!, MO!); along road Pifo-Papallacta, E of Paso de la Virgen, 00°21'S, 078°11'W, 3750–3850 m, 21 June 1985, Lægaard 54558B (AAU!); 54558C (AAU!); 54558D (AAU!); 54559 (AAU!, MO!, QCA!); 54560 (AAU!, MO!); 54561 (AAU!); road Quito–Baeza, 7–8 km NW of Laguna de Papallacta (Páramo de Guamaní), 00°19'S, 078°08'W, 3800 m, 20 July 1976, Øllgaard 8156 (AAU!, MO!, NY); Reserva Ecológica Oyacachi, 00°17'46"S, 078°08'49"W, 3927 m, 20 September 2008, Romoleroux 5194 (MO!, QCA!); carretera Quito–Baeza, páramo above Papallacta, 00°21'S, 078°10'W, 3400–3700 m, 28 May 1987, van der Werff 9638 (AAU!, GB, MO!). Pintag, Paso de Guamaní, quebrada, about +-4 km E Paso de Guamaní, on road to Papallacta, 00°20'S, 078°20'W, 3900 m, 26 March 1967, Sparre 15029 (AAU!, S). Quijos, Parroquia Papallacta, 00°21'S, 078°11'W, 3700 m, 28 May 1990, Cerón 10054 (MO!); Reserva Ecológica Antisana, carretera Pifo-Baeza, Páramo de la Virgen, 00°20'S, 078°12'W, 3960 m, 23 November 1998, Freire 2852 (AAU!, ILLS, MO!, QCNE); Reserva Ecológica Antisana, carretera Pifo–Baeza, Páramo de la Virgen, 00°23'S, 078°12'W, 3730 m, 24 November 1998, Freire 2870 (ILLS, MO!, QCNE); Reserva Ecológica Antisana, Páramo de Guamaní, carretera Pifo-Papallacta, La Virgen, 00°20'S, 078°12'W, 4140 m, 24 July 1998, Vargas 1946 (AAU!, ILLS, MO!, QCNE); carretera Quito-Tena via Baeza km 52, 3820 m, 03 August 1984, Dodson 14832 (MO!); 8 kms de la población de Oyacachi, siguiendo el sendero hacia Cochapamba, 3500 m, 12 March 1991, Gavilánez 462 (QCA!); carretera Oyacachi-Papallacta, colecciones a 11 km de la Laguna de Loreto, 3800 m, 27 April 1998, Guerrón 343 (QCA!); Papallacta, 3400–3600 m, 16 August 1990, Jaramillo 11832 (AAU!, MO!); Papallacta, 3400 m, 17 August 1990, Jaramillo 11842 (MO!); Páramo de Guamaní, road Quito Papallacta, 4000 m, 04 March 1979, Kieft 228 (QCA!); 3 km E of Paso de la Virgen on road Pifo-Papallacta, 3951–4050 m, 06 February 1985, Lægaard 54452 (QCA!); along road Pifo-Papallacta, E of Paso de la Virgen, 3750 m, Lægaard 54558 (QCA!); along road Pifo-Papallacta, E of Paso de la Virgen, 3750–3850 m, 21 June 1985, Lægaard 54560 (QCA!); N of Volcán Los Puntos, 3850 m, Lægaard 54756 (QCA!); N of Volcán Los Puntos, 3850–3900 m, 28 July 1985, Lægaard 54757 (QCA!); N of Volcán Los Puntos, 3851–3900 m, 28 July 1985, Lægaard 54758 (QCA!); 54759 (QCA!); Oyacachi, Yarupaccha, 3620–3680 m, 16 January 1996, Navarrete 1449 (QCA!); Reserva Ecológica Oyacachi, 3940 m, 28 January 2007, Romoleroux 4282 (QCA!); 4297 (QCA!); Reserva Ecológica Oyacachi, 3895 m, 23 February 2007, Romoleroux 4340 (QCA!); Reserva Ecológica Oyachachi, 3465 m, 08 March 2008, Romoleroux 4751 (QCA!); Páramo de Guamaní, alrededores de la laguna de Papallacta, 3900–4000 m, 06 December 1987, Romoleroux 491 (AAU!, NY, QCA!); Reserva Ecológica Oyachachi, 3929 m, 13 September 2008, Romoleroux 5167 (QCA!); 3681 m, 06 February 1985, Romoleroux 5168 (QCA!); 3917 m, 14 April 2009, Romoleroux 5475 (QCA!); 3880 m, 16 May 2009, Romoleroux 5489 (QCA!); Reserva Ecológica Oyacachi, 3560 m, 2 February 2007, Romoleroux A4321 (QCA!); Páramo de la Virgen, 3904 m, 29 September 2004, Salgado 1 (QCA!); about 3 km W of Oyacachi, 3550 m, 27 March 1996, Ståhl 2278 (QCA!); crescit prope Bambasacha in declivibus orientalibus mentis Quilindaña sitis, 3700 m, s.d., Stübel 204 (B, F!, MO!, NY, US!). Pichincha: Cayambe, carretera Cayambe-Hda. Piamonte-Patapamba, 00°02'S, 078°04'W, 3700 m, 04 December 1993, Freire 2606 (AAU!, QCA!). Papallacta, Along road Pifo-Papallacta, E of Paso de la Virgen, 00°21'S, 078°11'W, 4200–4300 m, 20 June 1985, Lægaard 54558A (AAU!); Pichincha-Napo, base del Volcán Antisana, entrada por Pintag hacia laguna Micacocha, campamento de EMAP, 00°27'S, 078°10'W, 4000–4100 m, 09 October 1990, Romoleroux 1117 (AAU!, QCA!); Pichincha-Napo, base del Volcán Antisana, entrada por Pintag hacia laguna Micacocha campamento EMAP, 00°27'S, 078°10'W, 4000–4100 m, 09 October 1990, Romoleroux 1118 (AAU!, QCA!); Páramo de la Virgen, camino antiguo, 0°20'S, 78°12'W, 3938 m, 20 September 2004, Salgado 3A (QCA!). Pifo, Mount Guamaní, 0°20'S, 78°33'W, 3600–3800 m, 15 September 1939, Asplund 8767 (QCA!); 2 km west of La Virgin on the road from Pifo to Papallacta, 00°17'S, 078°12'W, 3950–4050 m, 20 May 1984, Brandbyge 42638 (AAU!, MO!); Pifo-Papallacta (new road) app. 1 km W of Paso de la Virgen, 00°19'S, 078°13'W, 3700 m, 16 April 1992, Lægaard 102327 (AAU!, GOET!); 2 km S of Paso de la Virgen on road Quito-Baeza, 00°20'S, 078°13'W, 4000–4200 m, 19–20 May 1984, Lægaard 52134 (AAU!); 52135 (AAU!); 52138 (AAU!, MO!); 52162 (AAU!); 52176 (AAU!, QCA!); road Pifo–Papallacta, near Paso de la Virgen, 00°19'S, 078°13'W, 4000–4100 m, 13 March 1985, Lægaard 53849 (AAU!, MO!, QCA!); road Pifo-Papallacta, 3 km W of Paso de la Virgen, 00°18'S, 078°14'W, 3700–3900 m, 07 August 1985, Lægaard 54901A; 54901B; 54901C; 54901D; 54902AA; 54902K; 54902M; 54902P; 54902S; 54902U; 54902W; 54902Y (AAU!); at Paso de la Virgen, 00°18'S, 078°12'W, 4000–4050 m, 28 November 1985, Lægaard 55729 (AAU!, GOET!, MO!); carretera Quito–Papallacta, 1 km al este de la cumbre (La Virgen), 00°20'S, 078°15'W, 3800 m, 06 October 1986, Neill 7378A (AAU!, MO!, QCA!); 2 km al E de la cumbre de la carretera Pifo-Papallacta (La Virgen), 00°20'S, 078°15'W, 3900 m, 28 November 1987, Neill 8018 (AAU!, GB, MO!, QCA!, QCNE); Vía Baeza, 1 km antes del cruce de la Virgen, 00°18'S, 078°12'W, 3950 m, 01 March 1989, Palacios 3994 (AAU!, MO!); carretera Quito-Papallacta km 40–53, 00°16'S, 078°15'W, 3300–3800 m, 27 December 1992, Romoleroux 1507 (AAU!, QCA!); 00°21'S, 078°13'W, Romoleroux 353 (QCA!); Páramo de Guamaní, on the left side of the road Quito-Papallacta, 0°19'S, 78°12'W, 4000 m, 28 June 1997, Sklenár 2019 (QCA!). Quito, Parroquia Pifo, carretera Quito–Baeza, Páramo de la Virgen, 00°14'S, 078°20'W, 3500–3900 m, 25 April 1992, Cerón 18792 (MO!); Jameson 16 (MO!); road from Quito via Pifo to Papallacta, 00°34'S, 078°19'W, 3950 m, 04 July 2014, Kessler 14602; 14603; 14604; 14605 (Z!); Pass on Quito-Papallacta road, 3800–3900 m, 06 April 1991, Kessler 2750 (GOET!); 2755 (GOET!); Páramo de Guamaní, carretera Pifo-Papallacta, Km 27, 00°19'S, 078°12'W, 3960 m, 13 June 1990, León 1149 (QCA!); Baeza-Quito km 53, 00°20'S, 078°12'W, 4200 m, 08 July 2002, Schmidt-Lebuhn 378 (GOET!, QCA!). Tabacundo, at highest pass on road Mojanda-Tabacundo, 00°07'N, 078°15'W, 4030 m, 08 April 2001, Lægaard 21538A; 21538B (AAU!). Tocachi, Páramo de Mojanda, at Laguna Negra and S-side of Laguna Grande, 00°08'N, 078°16'W, 3800 m, 14 May 1985, Lægaard 54316B (AAU!, MO!, QCA!); 54330 (AAU!, MO!); 54333 (AAU!, MO!, QCA!); 54336 (AAU!); 54346 (AAU!, MO!, QCA!); Lagunas Mojanda, 00°07'N, 078°16'W, 3800 m, 30–31 Jul 1992, Palacios 10210 (AAU!, MO!); 10239 (AAU!, MO!); Lagunas de Mojanda, ca. Laguna Grande, 00°08'N, 078°16'W, 3700–3800 m, 01 June 1988, Romoleroux 654 (AAU!, QCA!); 3400–3500 m, Acosta-Solís 8379 (F!); 3700–4000 m, s.d., Asplund 18244 (S); alrededores de la Laguna Grande de Mojanda Cajas, 3960 m, 27 February 1999, Jaramillo 20986 (QCA!); the pass on Quito-Papallacta road, 3800–3900 m, 06 April 1991, Kessler 2749 (GOET!, MO!); 2750 (GOET!, MO!); 2753 (GOET!, MO!); 2754 (GOET!, LPB, MO!); Páramo de la Virgen, 3100 m, 01 November 2006, Muñoz 4 (QCA!); Laguna grande de Mojanda-Cajas, 3800 m, 19 September 2011, Pérez 5117 (QCA!); 3960 m, 01 August 1975, Little 22 (MO!).

Polylepis serrata Pilg., Bot. Jahrb. Syst. 37: 536. 1906.

Figs 22, 23

Polylepis serrata var. parcipila Bitter, Bot. Jahrb. Syst. 45: 593. 1911. Type. Peru. Cusco: La Convencion, Yanamanche, between Cusco and Santa Ana, 3500–3800 m, Weberbauer 4954 (holotype: B destroyed; isotype: Vratisl).

Polylepis serrata var. psilanthera Bitter, Bot. Jahrb. Syst. 45: 593. 1911. Type. Based on Polylepis serrata Pilg.

Type

Peru. Huanuco: Huamalics, southeast of Monzon, 3400–3500 m, 1903, Weberbauer 3354 (holotype: B destroyed; photos at MO!, US).

Figure 22. 

Polylepis serrata Pilg A inflorescence B flowering branch C leaves D fruit E inflorescence. Scale bars: 5 mm (A); 3 cm (B); 2 cm (C); 1 cm (E); 3 mm (D). Photographs by E.G. Urquiaga F.

Description

Trees 3–27 m tall. Leaves slightly congested at the branch tips, imparipinnate with 4–7 pairs of lateral leaflets, obtrullate in outline, (5.4–)6.7–8.7(–11.1) × (3.2–)3.9–5.7(–6.4) cm; rachises densely tomentose; points of leaflet attachment with a ring of short tomentose hairs around; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair (1.8–)2.4–3.5 × 0.8–1.0(–1.2) cm; margin serrate with 4–5 teeth, apically acute, basally unequally cordate; upper leaflet surfaces glabrous or sparsely lanate mainly in the mid-vein depression; lower leaflet surfaces densely lanate with whitish hairs 0.7–1.2 mm long. Inflorescences pendant, (7.6–)9.5–13.3(–17.3) cm long, bearing 16–35 flowers; floral bracts 3.4–4.5 mm long, narrowly triangular, densely villous on the outer surface; rachises villous. Flowers 5.2–5.9 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens (4–)6–14, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.2–2.3 mm long. Fruits turbinate, with variable numbers and placement of thin spines, densely villous; (3.8–)6.1–6.7 × 5.6–8.8 mm including spines. Diploid.

Figure 23. 

Polylepis serrata Pilg A flowering branch B fruit C lower leaf surface D upper leaf surface (A, B Arce s.n C, D Toivonen 90). Scale bars: 3 cm (A, C, D); 4 mm. Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis serrata is distributed from San Martín to Cusco, Peru (Fig. 24), where it occurs at 2000–3950 m elevation. It grows in relatively wet habitats usually mixed with or at the upper edge of the montane cloud forest, commonly with species of the genera Oreopanax and Weinmannia (Young 1993). It often also co-occurs with P. canoi and towards its upper distribution grades into forests of P. rodolfovasquezii (Boyle 2001; Kessler et al. 2014). This is one of the tallest Polylepis species, with heights of up to 27 m and diameters of up to 80 cm recorded (Toivonen et al. 2011). In a study in Cuzco, Peru, vegetative reproduction was found to be absent at 3000 m, but increased to around 80% at 3500–3800 m (Toivonen et al. 2011). Based on pollen records, Polylepis of presumably this species was common at Laguna de Chochos in San Martín, Peru, at the beginning of the Holocene some 10,000–6,000 bp and later declined (Bush et al. 2005). The ecophysiology of this species has been studied by Toivonen et al. (2014; as P. pauta).

Figure 24. 

Geographical distribution of the species of the subsections Lanuginosae, Pauta and Pepea.

Conservation status

The EOO for Polylepis serrata is estimated as 68,454 km2, the AOO is assessed at 100 km2 and it occurs at 18 locations. In Peru, was categorized as Near Threatened (SERFOR 2006, as P. pauta). It is restricted to small areas of eastern Peru where it is protected within Río Abiseo and Manu National Parks. However, the habitat of P. serrata is threatened by fires and forest destruction. We assess this species as Vulnerable (B1a+B2a, C1).

Notes

This species is quite similar to P. pauta and, in fact, it was treated as a junior synonym by Simpson (1979). Nevertheless, Simpson already pointed out the morphological diagnosability of geographical populations of P. pauta as defined by her. We consider that the recognition of P. serrata is justified, based on morphological, ecological and geographical grounds, and suggest that this taxon should be re-instated at species level. Polylepis serrata differs from P. pauta by having longer leaflets (1.8–3.5 cm versus 1.7–2.2 cm long) with different type and relatively shorter hairs (0.7–1.2 mm, lanate versus 0.9–1.9 mm, sericeous). Polylepis serrata further has shorter styles (1.2–2.3 mm; P. pauta: 2.3–2.5 mm).

Polylepis serrata also is morphologically similar to P. ochreata, with which it shares the number of leaflets (4–7 pairs). The most obvious differences between P. serrata and this species are the leaflet width, margin, apex and hair type and length, with P. serrata having elliptic leaflets 0.8–1.2 cm long, with acute apex and longer lanate hairs (0.7–1.2 mm) on the lower surface, whereas P. ochreata has narrowly elliptic leaflets 0.5–0.7 cm long, emarginate apex and short sericeous hairs (0.3–0.5 mm) on the lower surface.

Specimens examined

Peru. Cusco: Calca, Lares Cuncani, 07 June 1991, Tupayachi 1505 (CUZ!). La Convención, Prov. Machupicchu, Chakimayu, 3235 m, 01 September 2002, Arce s.n (CUZ!, USM!); Batiyayoc 13°08'01"S, 072°19'45"W, 3705 m, 01 October 2002, Arce s.n (CUZ!); Dist. Santa Teresa, Uchuyillaspay, 13°07'23"S, 072°37'30"W, 3883 m, 22 September 2005, Huamantupa 7018 (CUZ!, MO!); Dist. Echarate, Huayopata, San Luis, 13°04'43"S, 072°23'25"W, 2800 m, 30 March 2006, Huamantupa 7526 (CUZ!, MO!, USM!); Potrero, Bosque de Ukumuriyoc, 3600 m, 01 October 2002, Palomino 1737 (QCA!); Dist. Huayopata, Panticalle, Abra Málaga 13°08'02"S, 072°19'41"W, 3690 m, 30 May 2006, Toivonen 88 (CUZ!); 89 (CUZ!); 90 (CUZ!); 91 (CUZ!); Cerca Canchayoc, 3600 m, 29 June 1967, Vargas 19872 (CUZ!); Canchayoc, 3650–4000 m, 10 January 1968, Vargas 20086 (CUZ!); Canchayoc, 3700 m, 23 April 1980, Vargas 23311 (CUZ!); Yanamanche Quellomayo, 3600–4000 m, 25 July 1944, Vargas 4457 (CUZ!). Paucartambo, Challabamba, Pumataki, 13°09'16"S, 071°38'33"W, 3671 m, 10 December 2014, Boza 3024 (USM!, Z!); Challabamba, between Acjanaco and Tres Cruces, 13°10'07"S, 071°37'58"W, 3450 m, 10 December 2014, Boza 3025 (USM!, Z!); Trocha Ericsson, Acjanaco, Parque Nacional Manu, 3250–3350 m, 01 September 1990, Cano 4041 (USM!); Qollatambo, Parque Nacional Manu, 3700–3800 m, 10 September 1990, Cano 4319 (USM!); Tres Cruces, Parque Nacional Manu, 3600–3700 m, 06 March 1991, Cano 4588 (USM!); Cerro Chapuyoc, Challabamba, ParqueNacional Manu, 3350–3450 m, 15 March 1991, Cano 4689 (USM!); Valle del Pilcopata, near Accanaco Pass, turnoff to Tres Cruces,13°13'S, 071°35'W, 3500 m, 15 December 1983, Foster 7548 (MO!, USM!); Acjanaco, Parque Nacional Manu, Trocha Ericsson, 3000–3200 m, 22 July 1991, Huapaya 221 (USM!); Region of Acanacu and the Cordillera or Tres Cruces, 3290–3500 m, 07 December 1978, Luteyn 6386 (AAU!, MO!, USM!); Pillahuata, alrededores, Tres cruces, 130 km de Cusco en el camino hacia Pilcopta, 13°05'S, 071°30'W, 2000 m, 04 April 1987, Núñez 7749 (CUZ!, MO!, USM!); Km 130 hacia Kosñipata; incluye Acjanacu, Pillahuata, parte alta del Parque Nacional del Manu y ceja de selva hacia Kosñipata, 13°05'S, 071°30'W, 2600 m, 30 October 1987, Núñez 8482 (CUZ!, MO!); Tres Cruces, Parque Nacional Manu, 3500–3700 m, 01 April 1989, Tovar 10081 (USM!); Abra de Acjanaco-Tres Cruces de Oro, carretera Acjanaco-Pillahuata, 13°07'S, 071°40'W, 3700 m, 13 November 1986, Tupayachi 44; Tupayachi 45 (CUZ!, MO!); Entre Paucartambo y Acjanacu, Abra de Acjanacu, 3500 m, 25 January 1960, Vargas 13130 (CUZ!); Hda. Pillco, Valle de Paucartambi, 2800 m, 12 April 1967, Vargas 19242 (CUZ!); Abra de Acjanacu, 3500 m, 20 June 1986, Vargas 24009 (CUZ!); Quebrada de Acjanacu, 3500 m, 11 December 1942, Vargas 3004 (CUZ!, MO!); Chacapampa, 1800–2000 m, 01 December 1950, Vargas 9909 (CUZ!, MO!). Quispicanchis, Marcapata; 176 km from Cusco on road to Maldonado, Marcapata remmant forest to Cocha, 13°25'S, 070°54'W, 3150 m, 08 March 1991, Núñez 13151 (CUZ!, MO!); entre Abra Walla Walla y Marcapata a 210 km de Cusco, 13°25'S, 070°54'W, 2800–4600 m, 21–25 April 1988, Núñez 9032 (CUZ!, IBE, MO!); Huaillai-Marcapata, junto al río Araza, 2900 m, 11 December 1943, Vargas 3765 (CUZ!); Marcapata, 15–16 February 1929, Weberbauer 7803 (A!, MO!). Urubamba, Pakaymayu, 13°14'11"S, 072°29'38"W, 3861 m, 01 June 2002, Arce s.n (USM!); entre San Luis y Abra Malaga, 13°06'S, 072°22'W, 3500 m, 16 October 2002, Lehnert 444 (GOET!); Machu Picchu’, in Urcoscancha, a pampa above the village of Palcay, 13°09'30"S, 072°31'53"W, 3645 m, 05 July 1982, Peyton 792 (MO!); Lado Oriental de Cumbre Málaga, 01 October 1984, Rivas s.n (USM!); Machupicchu, campamento (km 90), 13°11'17"S, 072°26'10"W, 3070 m, 02 August 2006, Toivonen 1 (CUZ!); Dist. Machupicchu, campamento (km 90), 13°11'17"S, 072°26'10"W, 3070 m, 02 August 2006, Toivonen 2 (CUZ!); Dist. Machupicchu, Pakaymayu, 13°14'9"S, 072°29'36"W, 3760 m, 24 August 2006, Toivonen 24, 25; 26; 27; 30 (CUZ!); Dist. Machupicchu. Pakaymayu, 13°14'9"S, 072°29'36"W, 3760 m, 13 September 2006, Toivonen 3760 (CUZ!). Huánuco: Pachitea, Dist. de Umari, Comunidad Campesina de San Marcos, 3400 m, 04 March 2010, Beltrán 6740 (USM!); 6760 (USM!); 01 July 1903, Weberbauer 3354 (B, MO!). Junín: Satipo, Cordillera Vilcabamba, Río Ene slope, near summit of divide, 11°39'36"S, 073°40'02"W, 3320 m, 14 June 1997, Boyle 4398 (USM!). San Martín: Mariscal Caceres, Primer derrumbe y laguna del pato y asociadas del P. N. del Río Abiseo, 3250–3450 m, 24 June 1996, Cano 7265 (USM!); Dist. de Huicungo, Parque Nacional Río Abiseo, Callejón Rojas, 3600–3700 m, 06 July 2011, Castillo 1026 (USM!); 959 (USM!); Dist. de Huicungo, zona de Alpamachay, 3200–3300 m, 14 June 2001, León 5224 (USM!); Río Abiseo National Park; forest on edge of Laguna de Chochos, NW corner of park, 07°00'S, 077°00'W, 3300 m, 19 May 1986, Young 3175 (F!, MO!, USM!); Río Abiseo National Park, jucture of Quebrada Misquichilca and Quebrada Quimar, 4 km SE of Condormarca, 07°00'S, 077°00'W, 3500 m, 05 June 1986, Young 3552 (F!, MO!, USM!); forest on the edge of Laguna de Chochos, Chochos, NW corner of Río Abiseo National Park, 07°S, 077°W, 3300 m, 17 July 1987, Young 4863 (MO!, USM!).

Sericeae T.Boza & M.Kessler, sect. nov.

Diagnosis

Trees; 2–7 lateral leaflet pairs; lower leaflets sericeous or villous; fruits with flattened spines, densely sericeous or villous.

Type

Polylepis sericea Wedd.

Note

The subsectional epithet Sericeae is a plural adjective agreeing in gender with Polylepis.

Polylepis albicans Pilger, Bot. Jahrb. Syst. 37: 535. 1906.

Figs 25, 26

Type

Peru. Ancash: Cordillera Blanca above Caraz, Jun 1903, Weberbauer 3229 (holotype: B destroyed; photos at F!, GH!, NY!).

Figure 25. 

Polylepis albicans Pilger A inflorescence B lower leaflet surface C upper leaflet surface D branch apex with young inflorescence E young inflorescence (A Boza & Urquiaga 3014 B Boza & Urquiaga 3013 C–E Boza & Urquiaga 3015). Scale bars: 1 cm (A, B, C); 2 cm (D); 0.4 cm (E). Photographs by E. G. Urquiaga F.

Description

Trees 3–7(12) m tall. Leaves strongly congested at the branch tips, imparipinnate with 3–4 pairs of lateral leaflets, obtrullate in outline, 3.5–4.9 × (2.5–)2.8–3.4 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight hairs, with ferruginous resin at leaflet insertion; stipular sheaths apically acute with spurs, densely sericeous on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.4–2.0 × 0.4–0.7 cm; margin slightly crenate at the apex with 4–5 teeth, strongly revolute, coriaceous, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous or sparsely sericeous; lower leaflet surfaces densely sericeous with short silky hairs 0.3–0.5 mm long. Inflorescences pendant, 3.9–6.6(7.5) cm long, bearing 18–21 flowers; floral bracts 5.5–6.9 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 3.4–7.5 mm diam.; sepals 3–4, ovate, green, densely sericeous outside; stamens 7–18, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.4–3.2 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 3.1–5.6 × 2.3–5.6 mm including spines. Diploid.

Figure 26. 

Polylepis albicans Pilger A flowering branch B fruit C lower leaf surface D upper leaf surface (A Boertman 53 B Smith 8210 C Schimidt-Lebuhn 510 D Lasermann II11). Scale bars: 4 cm (A); 5 mm (B); 1.5 cm (C, D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis albicans occurs in north-western Peru in the Cordillera Blanca in Ancash and in the adjacent high Andes of La Libertad (Fig. 41). It grows in semi-humid montane forest at 3400–4950 m elevation, often alongside P. weberbaueri (Fig. 41). Where they co-occur, P. albicans tends to grow at lower elevations (maximum probability of occurrence at 3750–3900 m) than P. weberbaueri (4400 m) (Morales et al. 2018) and to generally grow in warmer and drier habitats than P. weberbaueri (Sevillano-Ríos and Morales 2021). Along with this, seedling density of P. albicans decreases with elevation, whereas that of P. weberbaueri increases (Morales et al. 2018). At 4350–4700 m elev. in Paria Valley, most trees of P. albicans are 4–7 m tall (maximum 10–12.5 m) with diameters of 10–20 cm (maximum 50–60 cm) (Castro and Flores 2015). The Polylepis forests in this region harbor diverse bird communities with a substantial proportion of threatened species, some of which are specialized to Polylepis forests (Sevillano-Ríos et al. 2011; Sevillano-Ríos and Rodewald 2017, 2021).

Conservation status

The Extent of Occurrence (EOO) for P. albicans is estimated as 13,028 km2, the area of occupancy (AOO) is assessed at 164 km2 and it is known from 24 locations. It occurs in Huascarán National Park which encompasses almost the entire Cordillera Blanca. However, illegal mining occurs within the Park, becoming a direct threat to the species. Polylepis albicans is subject to reforestation activities in Huascarán National Park (Fuentealba and Sevillano 2016). We assess the species as Vulnerable (B1a+B2a).

Notes

This species was described by Pilger (1906), based on material from Caraz, Cordillera Blanca, Peru. It was synonymized under P. sericea by Simpson (1979) who mentioned that populations of P. sericea from the Cordillera Blanca are distinct by having leaflets with pronounced pubescence in both sides. Based on its distinct morphology and ecology, this taxon was re-instated at species level by Boza Espinoza et al. (2019). Polylepis albicans differs from P. sericea by a sparse to dense sericeous hair cover on the upper leaflet surfaces and on the leaf rachises (versus glabrous in both cases in P. sericea), shorter hairs (0.3–0.5 mm versus 0.7–1.0 mm) and commonly reddish glandular hairs at leaflet bases (lacking in P. sericea). Occasionally, specimens of P. albicans resemble those of P. argentea in leaflet shape, but leaflet margins are slightly crenate in P. albicans and entire in P. argentea. Further, P. argentea differs from P. albicans by the lower number of flowers in the inflorescence (5–9 versus 18–21).

To us, the reddish glands, thick leaf texture and often emarginated leaflet apices suggest that P. albicans may include some genetic elements from P. weberbaueri, with which it co-occurs, but this remains to be tested by molecular studies.

Specimens examined

Peru. Ancash: Carhuaz, Sonquenua, Shilla, 4020 m, 21 December 1989, Arce & Sánchez 188 (MO); Valley of Río Marcará, 2.5 hours from Vicos on trail to Lejiacocha, 09°19'00"S, 077°31'00"W, 3600 m, 11 March 1964, Hutchison & Wright 4325 (F, MO, USM); Shacshicucho, 4050 m, 26 August 1978, Mostacero et al. 569 (MO); Huascarán National Park; Quebrada Ulta, north side of valley; S-facing, moderate to gentle slopes, 09°07'S,077°32'W, 3930 m, 29 July 1985, Smith 11410 (MO, USM); Huascarán National Park. N-side of main valley, Quebrada Honda, 09°18'S, 077°25'W, 4200 m, 03 October 1985, Smith et al. 11641 (F, MO, USM); Huascarán National Park, mouth of Quebrada Ishinca, 09°23'S, 077°29'W, 3880 m, 15 February 1985, Smith et al. 9597 (F, MO, USM). Huaraz, Quebrada Quillcayhuanca, 4200 m, 30 October 1989, Arce & Martel 163 (MO); Quilcayhuanca, 09° 29'53.8"S, 77°24'59.6"W, 3831 m, 08 November 2014, Boza & Urquiaga 3022 (USM, Z); Lance, 4500 m, 04 June 2015, Boza &Urquiaga 3144 (USM, Z); Llanganuco, 09°04'47"S, 077°38'36"W, 4445 m, 03 June 2015, Boza & Urquiaga 3145 (USM, Z); 3146 (USM, Z); 3147 (USM, Z); Ulta, 09°06'S, 077°32'W, 4300 m, 07 June 2015, Boza & Urquiaga 3152 (USM, Z); 3153 (USM, Z); Llaca, 09°26'S, 077°26'W, 07 June 2015, Boza & Urquiaga 3154 (USM, Z); 3155 (USM, Z); Boza & Urquiaga 3156 (USM, Z); 28 May 1982, Cerrate 7696 (MO, USM); Comprado en la feria de plantas medicinales de Huaraz, 07 July 1988, Cerrate 9123 (USM); Huascarán National Park, Quebrada Shallap, 09°30'S, 077°24'W, 3900 m, 20 February 1985, Smith et al. 9709 (F, MO, USM). Huari, Llanganuco, 4366 m, 29 November 2007, Lasermann I12 (USM); Huascarán National Park, southside of Quebrada Carhuazcancha, 09°28'S, 077°15'W, 4200 m, 06 May 1986, Smith et al. 12255 (MO, USM); Huascarán National Park, Quebrada Pachachaca, a lateral valley of Quebrada Rurichinchay, 09°27'S, 077°16'W, 3860 m, 12 June 1986, Smith et al. 12542 (F, MO); Huascarán National Park, Quebrada de Yuraccocha, a lateral valley of Quebrada Rurichinchay, 09°22'S, 077°17'W, 4300 m, 16 June 1986, Smith et al. 12737 (MO, USM); Acopalca, 09°20'25"S, 077°12'19"W, 3300 m, 11 August 2010, Xue-Jun 194 (USM). Huaylas, Paron, 09°02'13"S, 77°43'52"W, 3357 m, 07 November 2014, Boza & Urquiaga 3016 (USM, Z); Huascarán National Park, Quebrada Parón, 09°01'S, 077°43'W, 3760 m, 08 May 1985, Smith 10606 (MO); Huascarán National Park, 09°00'S, 077°41'W, 4200 m, 29 September 1985, Smith 11537 (MO, USM); Huascarán National Park, Parón Valley, 09°00'S, 077°42'W, 4150 m, 01 January 1985, Smith & Goodwin 8924 (AAU, F, MO, USM); Huascarán National Park, Parón Valley, 09°01'S, 077°43'W, 3700 m, 01 January 1985, Smith & Goodwin 8939 (MO, USM); Huascarán National Park, western flank of Cordillera Blanca, Alpamayo–Cashapampa trail, 08°53'S, 077°45'W, 3950 m, 13 March 1985, Smith & Valencia 10013 (MO, USM); Huascarán National Park, lower slopes of Cerro Pakla, 08°49'S, 077°57'W, 4300 m, 09 April 1986, Smith et al. 12055 (AAU, F, MO, USM); Huascarán National Park, Quebrada Santa Cruz at base of and entering Quebrada Artizonraju, 08°55'S, 077°36'W, 4800 m, 16 January 1985, Smith et al. 9298 (F, MO, USM). Yungay, Ruta Vaqueria–Portachuelo, 3900 m, 05 November 1989, Arce 165 (MO); Huaytajirca, en el Dist. de Yanama, procedencia Matca (Yanama), 16 December 1989, Arce & Abilio 186 (MO); 30 km, hacia arriba, Parque Nacional de Huascaran, 3850 m, 10 March 1983, Beck 7914 (GOET, MO); Llanganuco, 09°03'04"S, 77°36'42"W, 3852 m, 07 November 2014, Boza & Urquiaga 3013 (USM, Z); Llanganuco encima de Yungay, 4000 m, 27 June 1966, Ferreyra 16860 (MO); Llanganuco arriba de Yungay, 4200 m, 14 December 1967, Ferreyra & Blount 18727 (GOET, MO, USM); Llanganuco, arriba de Yungay, 3900 m, 22 October 1965, Ferreyra & Tryon 16503 (MO, USM); slopes below Laguna de LLanganuco in quebrada de Llanganuco ca. 25 km above Yungay, just above and below the lake, 4100 m, 27 June 1966, Gabriel & Schunke 3826 (A, F); Dist. Yungay, Laguna de Llanganuco, 3800 m, 17 February 1968, Gutiérrez 249 (F); Laguna de Llanganuco, 3800 m, 19 February 1968, Gutiérrez 249-AGR (MO); Quebrada Llanganuco, cerca de la laguna y el albergue, 3850 m, 04 July 1981, Peréz 62 (USM); Laguna Llanganuco, 3400 m, 01 November 1984, Sagástegui & Dillon 12315 (F, MO); near Laguna Llanganuco, 09°03'54"S, 077°38'00"W, 4300 m, 14 August 2002, Schmidt-Lebuhn 507 (USM); near laguna Llanganuco, 09°03'54"S, 077°38'00"W, 4300 m, 14 August 2002, Schmidt-Lebuhn 510 (USM); Huascarán National Park, Lake Llanganuco, 09°05'S, 077°39'W, 3860 m, 16 August 1984, Smith 8210 (MO); Huascarán National Park, Llanganuco sector, Quebrada Demanada, side valley to Nevado Pisco, 09°02'S, 077°37'W, 4250 m, 13 April 1985, Smith & Cautivo 10302 (MO, USM); Huascarán National Park, Quebrada Ranincuray, 09°00'S, 077°33'W, 3850 m, 11 January 1985, Smith et al. 9049 (AAU, F, MO, USM); Huascarán National Park, Morococha at largest lake, 08°55'S, 077°35'W, 4550 m, 14 January 1985, Smith et al. 9215 (AAU, F, MO, USM); Llanganuco P. N. Huascarán, 09°07'00"S, 077°37'00"W, 3475 m, 07 August 2010, Xue-Jun 25 (USM). Cordillera Blanca near Ingenio in upper Pumapampa Valley, 11°04'S, 077°36'W, 4350 m, 15 February 1987, Boertmann 53 (AAU); Quebrada Ishinca, Cordillera Blanca, 09°23'S, 077°28'W, 3950 m, 23 August 1988, Frimer & Nielsen 101 (AAU); Quebrada Matará in Quebrada Ulta, Cordillera Blanca, 09°07'S, 077°32'W, 4250 m, 03 September 1988, Frimer & Nielsen 104 (AAU); Quebrada Ulta, Cordillera Blanca, 09°06'S, 077°32'W, 4050 m, 02 September 1988, Frimer & Nielsen 107 (AAU); 108 (AAU); Quebrada Rurichinchay, Cordillera Blanca, 09°21'S, 077°18'W, 4000 m, 06 Oct 1988, Frimer & Nielsen 118 (AAU); 123 (AAU); Quebrada Rurec, Cordillera Blanca, 09°25'S, 077°17'W, 3950 m, 11 October 1988, Frimer & Nielsen 125 (AAU); Frimer & Nielsen 126 (AAU); Quebrada Carhuasccancha. Cordillera Blanca, 09°29'S, 077°15'W, 3900 m, 15 October 1988, Frimer & Nielsen 132 (AAU); Querada Paron, Cordillera Blanca (W of Paron), 09°00'S, 077°41'W, 4150 m, 18 August 1988, Frimer & Nielsen 42; 43; 44; 45; 59 (AAU); Quebrada Ishinca, Cordillera Blanca, 09°23'S, 077°28'W, 3950 m, 23 August 1988, Frimer & Nielsen 70; 71; 73 (AAU); Quebrada Ishinca, Cordillera Blanca, 09°23'S, 077°28'W, 3950 m, 23 August 1988, Frimer & Nielsen 74; 99 (AAU); road from Yungay to Yauya, vicinity of Lagunas Llanganuco, 09°02'S, 077°35'W, 3800 m, 10 July 1982, Gentry et al. 37376 (MO, USM); Llanganuco, 4377 m, 29 November 2007, Lasermann II/1 (USM); Cordillera Blanca, Laguna Paron, 30 km NE of Caraz in northern Huascaran National Park, 4100 m, 10 October 1988, Peterson s.n (MO); Cordillera Blanca, East of Yungay, Laguna de Llanganuco, 3800 m, 05 April 1988, Renvoize & Lægaard 5066 (AAU); Cordillera Blanca. 35 km east of Yungay, 4000 m, 05 April 1988, Renvoize & Lægaard 5074 (AAU, MO); 5075 (AAU); 40 km east of Yungay., 4350 m, 05 April 1988, Renvoize & Lægaard 5088A; 5088B (AAU); Llanganuco Valley, 09°00'S, 077°30'W, 1500 m, August 1959, Tothill 174 (F); 3700 m, 1901–1929, Weberbauer 3229 (B, MO); Parque Nacional Huascarán. Llanganuco, 11 July 1982, Zardini 1535 (MO). La Libertad: Sánchez Carrión, señal Huayllides, 07°53'S, 078°02'W, 4100 m, 21 August 1982, Smith 2278 (MO, USM).

Polylepis argentea T.Boza & H.Quispe, Syst. Bot.44(2): 327. 2019.

Figs 27, 28

Type

Peru. Junín: Concepción, Dist. de Andamarca, a 2.5 km de la localidad de Alhuay, 11°41'30"S, 74°54'01"W, 4150 m, 10 Oct 2017, H.R. Quispe M. 85 (holotype: CUZ!; isotypes: USM!, Z!).

Figure 27. 

Polylepis argentea T.Boza & H.R. Quispe A flower B inflorescence C upper leaflet surface D lower leaflet surface E bark F branching patterns (A, C, D, F Boza & Urquiaga 3036 B, E Quispe 85). Scale bars: 3 mm (A); 3 cm (B); 1 cm (C, D). Photographs A, C, F T. E. Boza E. B, E H. R. Quispe D E. G. Urquiaga F.

Description

Trees 4–7 m tall. Leaves strongly congested at the branch tips, imparipinnate with 2 pairs of lateral leaflets, obtrullate in outline, (2.9)3.3–4.3 × (2.6–)3.3–4.3 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight hairs, sometimes with resin at leaflet insertion; stipular sheaths apically acute with spurs, densely sericeous on the outer surfaces; leaflets narrowly elliptic in outline, second pair from the terminal leaflet the largest, one of this pair (1.9)2.4–2.6 × 0.5–0.7 cm; margin entire, coriaceous, apically acute to slightly retuse, basally unequally cordate; upper leaflet surfaces almost glabrous with some hairs on the mid-veins to densely sericeous with silky hairs throughout; lower leaflet surfaces densely sericeous with silky hairs 0.6–0.9 mm long. Inflorescences pendant, 7.2–8.1 cm long, bearing 5–6(–9) flowers; floral bracts 4.5–5.6 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 7–9 mm diam.; sepals 3–4, ovate, green, densely sericeous outside; stamens 7–10, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.7–4.4 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 2.3–2.5 × 3.5–5.3 mm including spines. Diploid.

Figure 28. 

Polylepis argentea T.Boza & H.R. Quispe A flowering branch B fruit C lower leaf surface D upper leaf surface (A, C, D Quispe 85 B Quispe 87). Scale bars: 4 cm (A); 2 mm (B, C); 3 cm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis argentea has been found in central Peru at La Mar (Ayacucho), Concepcion, Huancayo and Satipo (Junin) and La Convencion and Urubamba (Cusco) (Fig. 41). It grows mainly in humid Andean Forest at 3400–4400 m elevation. It often co-occurs with P. canoi, P. rodolfovasquezii and P. serrata (Quispe-Melgar et al. 2018) and although hybrids are not yet known, these might occur. In the Cordillera Vilcabamba, Polylepis argentea dominates the forest, with P. canoi intermixed among it and P. serrata in hilltop forest (Boyle 2001). The slightly different colours of the foliage of each species of Polylepis make this gradation obvious even from a distance (Boyle 2001).

Conservation status

The estimated Extent of Occurrence (EOO) for P. argentea is 23,788 km2 and the Area of Occupancy is 40 km2. It is known from just eight locations, but several of these encompass forests of several square kilometers. Boyle (2001) described extensive forest of this species in the remote Cordillera Vilcabamba, which is largely protected in Otishi National Park. We assess Polylepis argentea as Vulnerable (B1a+B2a).

Notes

Polylepis argentea seems morphologically closest to P. sericea and P. canoi with which it shares similar lower leaflet surface hair type and density. The most obvious differences between P. argentea and these species is leaflet size, with P. argentea having leaflets of 1.9–2.6 × 0.5–0.7 cm, whereas P. canoi has leaflets of 2.4–3.9 × 0.8–1.5 cm and P. sericea of 1.8–2.1 × 0.8–1.0 cm. Further, P. argentea has shorter hairs (0.6–0.9 mm versus 1.3–1.7 mm) than P. canoi. In P. canoi, the hairs on the lower leaflet surfaces are yellowish and often most pronounced on the secondary veins, whereas in P. argentea, they are silky and more evenly distributed. Polylepis argentea has the upper leaflet surfaces with a few hairs on mid-veins whereas P. sericea has totally glabrous upper leaflet surfaces. Additionally, the inflorescence length and number of flowers per inflorescence differ between the species, with P. argentea having inflorescences 7.2–8.1 cm long with 5–9 flowers, compared with values of 3.3–4.5 cm and 9–15 flowers in P. sericea and 8.2–14.5 cm and 12–26 flowers in P. canoi. The three species can also be distinguished by the number of stamens and style length, with P. argentea having 7–10 stamens and styles 2.7–4.4 mm long, whereas the other two species have 13–15 stamens and styles 2.4–3.8 mm in P. canoi and 1.9–2.5 mm in P. sericea.

Polylepis argentea was first collected by B. Boyle during scientific expeditions carried out in 1997 and 1998 to the isolated Cordillera Vilcabamba where he recorded three species of Polylepis (Boyle 2001). The first one, here called P. argentea, he called Polylepis sp1 and described as “a tree of 4–5 m with rather small silvery-tomentose leaflets” (specimen Boyle 4149) dominating the forest. A second species of Polylepis (here P. canoi) “with fewer, darker green and nearly glabrous leaflet”, which he called Polylepis cf. sericea (Boyle 4151), occurred patchily within stands of Polylepis sp1, as well as in monospecific stands. The third species mentioned was Polylepis cf. pauta (here P. serrata) (Boyle 4398), described as “a common tall tree (to 25 m high) in the tall hilltop forest”.

Specimens examined

Peru. Ayacucho: La Mar, Dist. Tambo, Estera Community, sector Muyuorco, 12°54'19"S, 073°48'17"W, 3637 m, 29 June 2015, Boza 3036; 3096; 3097; 3098; 3099; 3100; 3101; 3102; 3103; 3104; 3105; 3106 (USM!, Z!). Cusco: La Convención, Dist. Huayopata Abra Málaga, 13°08'05"S, 072°19'18"W, 3802 m, 13 June 2015, Boza 3032; 3082; 3083; 3084 (USM!, Z!); Cuzco. Provincia La Convención, Bosque Qulcamachay, 4200 m, 01 October 2002, Palomino 2030 (QCA!); Dist. Huayopata, localidad Panticalle, Abra Málaga, 13°08'02"S, 072°19'32"W, 3725 m, 30 May 2006, Toivonen 84; 85; 86; 87 (CUZ!). Urubamba, Inkatambo, 13°18'06"S, 072°31'44"W, 4340 m, 01 September 2002, Arce s.n (USM!); Qésqa, 13°17'51"S, 072°24'57"W, 4000 m, 01 October 2002, Arce s.n (USM!); Abra Málaga, 13°08'43"S, 072°18'09"W, 4318 m, 01 October 2002, Arce s.n (CUZ!); Inkatambo 13°18'06"S, 072°31'44"W, 3840 m, 01 September 2002, Arce s.n (CUZ!); Dist. Ollantaytambo, Huaytampo, 13°10'47"S, 072°21'10"W, 3650 m, 07 November 2002, Calatayud 1035 (CUZ!, F!, MO!, USM!); Santuario Histórico Machu Pichu, camino Inca, Km 88–112, por puente Ruinas, 13°18'S, 072°07'W, 2000–4100 m, 20–21 June 1988, Núñez 9204 (MO!); Dist. Ollantaytambo, localidad Abra Málaga, 13°09'02"S, 072°18'09"W, 4230 m, 29 May 2006, Toivonen 15 (CUZ!); 16 (CUZ!); Dist. Ollantaytambo, localidad Huaytampo, 13°10'31"S, 072°21'03"W, 3800 m, 06 July 2006, Toivonen 95 (CUZ!); 96 (CUZ!). Junín: Concepcion, Andamarca, 11°41'30"S, 074°54'01"W, 2300 m, 14 June 2002, Martinez 18 (USM!); Dist. de Andamarca, a 2.5 km de la localidad de Alhuanay, 11°41'30"S, 074°54'01"W, 4150 m, 10 October 2017, Quispe 85 (CUZ!, USM!, Z!). Huancayo, Dist. de Santo Domingo de Acobamba, a 5 km de la localidad de Callanca, 11°45'43"S, 074°55'15"W, 4200 m, 12 October 2017, Quispe 87 (CUZ!, USM!, Z!). Satipo, Satipo/La Convencion Cordillera Vilcabamba Río Ene slope, near summit of divide, 11°39'30"S, 073°40'02"W, 3350 m, 07 June 1997, Boyle 4149 (USM!).

Polylepis canoi W.Mend., Rev. Peruana Biol. 12(1): 104–106. 2005.

Figs 29, 30

Type

Peru. Cusco: La Convención, Cordillera del Vilcabamba, 30 km caminando de la Hacienda Luisiana y del Río Apurimac, 3400 m, 17 Jul 1968, T.R. Dudley 11180 (holotype: MO!; isotypes: NA, F!).

Figure 29. 

Polylepis canoi W.Mend A flowers B upper leaflet surface C lower leaflet surface D flowering branch E bark F upper leaflet surface. Scale bars: 3 mm (A); 2 cm (B–D, F). Photographs A, B H. Huaylla C, D A. Fuentes E, F H. R. Quispe.

Description

Trees 4–7(9) m tall. Leaves strongly congested at the branch tips, imparipinnate with 2–3(4) pairs of lateral leaflets, obtrullate in outline, (4.0–)7.9–9.4 × (4.2–)6.7–7.5 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight yellowish hairs, with ferruginous resin at leaflet insertion; stipular sheaths apically acute with spurs, glabrous in both surfaces; leaflets obovate in outline, second pair from the terminal leaflet the largest, one of this pair (2.4–)3.4–3.9 × (0.8–)1.1–1.5 cm; margin entire to slightly serrate with 4–6 teeth, coriaceous, apically slightly emarginate, basally unequally cordate; upper leaflet surfaces glabrous or with sparse sericeous hairs; lower leaflet surfaces densely sericeous with yellowish hairs 1.3–1.7 mm long. Inflorescences pendant, 8.2–14.5 cm long, bearing 12–17(26) flowers; floral bracts 7.0–15.8 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 7.8–11.2 mm diam.; sepals 3–4, ovate, green, densely sericeous outside; stamens 13–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.4–3.8 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 5.2 × 7.5 mm including spines. Diploid.

Figure 30. 

Polylepis canoi W.Mend. A flowering branch B upper leaf surface C lower leaf surface D fruits E stipular sheaths (A Amez & Quispe s.n B, D, E Brandbyge 511 C Boyle 4151). Scale bars: 4 cm (A); 3 cm (B, C); 5 mm (D). Photographs by E. G. Urquiaga F.

Distribution, habitat and ecology

Polylepis canoi is distributed from the central-south-eastern Peruvian Andes to the central Bolivian Andes (Fig. 41). The species occurs in wet Andean Forest at 3150–4500 m elevation. It co-occurs with P. argentea and P. serrata in the Cordillera Vilcabamba in Peru, where it forms large pure stands and also grows intermixed with P. argentea (Boyle 2001). In Bolivia, where it was long known as P. sericea, it is only known from a few scattered localities where it has been recorded co-occurring with P. lanata (Kessler 1995b). In Peru, maximum tree height decreases from 9 m at 3700 m to 4 m at 4250 m elev. (Toivonen et al. 2011; as P. sericea). Along the same elevational gradient, the proportion of vegetative reproduction increases from 0% to 70% (Toivonen et al. 2011).

Conservation status

The EOO is estimated as 98,800 km2 and AOO as 84 km2. The species is known from 17 locations in Peru and Bolivia. In Peru, it has been categorized as EN (B1ab(iii)) (León-Yañez et al. 2006) and in Bolivia, as EN (B1ab(i,ii,iii)) (Arrázola et al. 2012, as P. sericea). Agricultural expansion, logging, cattle, burning of surrounding grasslands and mining are threats for this species (Arrázola et al. 2012). We assess Polylepis canoi as Endangered (B1a+B2a, C1).

Notes

Polylepis canoi seems morphologically closest to P. ochreata and P. sericea. However, it has obovate and larger (2.4–3.9 × 0.8–1.5 cm) leaflets than the other two species, which have elliptic and smaller (1.8–2.7 × 0.5–1.0 cm) leaflets. Additionally, P. canoi has longer hairs (1.3–1.7 mm) than the other two species (0.7–1.2 mm).

This species was treated as endemic to Peru by Mendoza (2005) when he described it. Boza Espinoza et al. (2019) revised its distribution to extend it to Bolivia. The specimens from Puno (Peru) and La Paz and Cochabamba (Bolivia) were previously determined as P. sericea (e.g., Kessler 1995a). Furthermore, the specimen cited by Schmidt-Lebuhn et al. (2006a) as the first record of P. pauta for Bolivia was re-identified as P. canoi by Boza Espinoza et al. (2019).

Specimens examined

Bolivia. Cochabamba: Chapare, Mayka Mayu, 17°12'S, 065°58'W, s.d., Hensen 2248 (BOLV, LPB, MO!, TEX); Maycamayu, ca. 60 Km N Sacaba, 17°12'S, 065°58'W, 3300 m, 11 August 1991, Kessler 2874 (GOET!); 2875 (GOET!); 2877 (GOET!); 2878 (AAU!); 2879 (GOET!, MO!); 2880 (GOET!). La Paz: Bautista Saavedra, Area Natural de Manejo Integrado Apolobamba, bajada de Waricunca, mas allá de Chaka, por el antiguo camino Sorapata-Apolo, 14°53'19"S, 068°47'04"W, 3550 m, 28 March 2009, Fuentes 13589 (BOLV, LPB, MA, MO!, USZ); Area Natural de Manejo Integrado Apolobamba, sector Chaka, bosque continuo al SE del campamento cerca de la cueva, por el antiguo camino Laji Sorapata-Apolo, 14°53'32"S, 068°47'12"W, 3461 m, 30 March 2009, Fuentes 13634 (LPB, MO!, QCA!, USZ); 13639 (BOLV, LPB, MO!, QCA!, USZ); Área Natural de Manejo Integrado Apolobamba. Bajada de Wuaricunca, más allá de Chaka, por el antiguo camino Hilo-Hilo – Apolo, 14°53'11"S, 068°47'04"W, 3550 m, 06 April 2009, Fuentes 13897 (BOLV, LPB, MA, MO!, QCA!, USZ); Area Natural de Manejo Integrado Madidi, Hilo Hilo. Sobre el Río Tumamayu en la localidad de Laji Sorapata, 14°53'14"S, 068°51'52"W, 4182 m, 10 April 2009, Loza 635A (LPB, MA, MO!); 645 (LPB, MO!, QCA!, USZ); Área Natural de Manejo Integrado Apolobamba, Hilo Hilo, Juchuy Queñua a medio día de Laji Sorapata, 14°54'52"S, 068°48'08"W, 3879 m, 16 April 2009, Loza 757 (LPB, MO!); 775 (BOLV, LPB, MA, MO!, USZ); 788 (LPB, MO!, QCA!, USZ); Chaka Machay(Laji), 14°53'S, 068°47'W, 3300 m, 14 September 2002, Zenteno 1507 (LPB). Franz Tamayo, Área Natural de Manejo Integrado Apolobamba, Keara bajo, 14°42'09"S, 069°04'35"W, 3500 m, 21 November 2007, Araujo 4078 (LPB, MO!); Área Natural de Manejo Integrado Apolobamba, Hilo Hilo, Chaka, sobre la senda hacia Amantala, 14°53'16"S, 068°47'16"W, 3576 m, 16 August 2009, Cayola 3417 (BOLV, LPB, MA, MO!, USZ); Parque Nacional Madidi, entre Queara y Mojos, sector Mosquito, 14°39'37"S, 068°57'54"W, 3400 m, 26 February 2008, Fuentes 12028 (BOLV, LPB, MO!, QCA!, USZ); Parque Nacional Madidi, Puina Viejo, ca. 3 km río abajo por camino al W del río, 14°34'58"S, 069°06'24"W, 3316 m, 21 June 2005, Fuentes 8549 (LPB, MO!); Parque Nacional Madidi, Hilo Hilo, arriba de la mina Kanupata en la localidad de Laji Sorapata, 14°52'28"S, 068°51'15"W, 4182 m, 11 April 2009, Loza 671 (BOLV, HSB, LPB, MA, MO!, NY, QCA!, USZ); Bosque de Queñuari, 14°54'31"S, 069°01'07"W, 4275 m, 28 September 2006, Palabral 489 (LPB); Senda Pelechuco-Mojo, sector Tambo Quemado, a media hora del campamento siguiendo senda Pelechuco Moxos, 14°41'03"S, 068°58'22"W, 3455 m, 01 May 2003, Paniagua 5710 (LPB, MA, MO!). Larecaja, bosque de a localidad de Hirola, pasando Lipichi, 15°26'41"S, 068°10'57"W, 3881 m, 05 November 2008, Palabral 705 (LPB). Murillo, 8 km after Palca on the road to Iquico, 4000 m, 10 November 1967, Vuilleumier 342 (MO!).

Peru. Cusco: La Convención, Cordillera de Vilcabamba, above Camp 7, ca. 30 km walking distance from Hacienda Luisiana and the Apurimac River, 12°30'S, 074°30'W, 3400 m, 17 July 1968, Dudley 11180 (F!, MO!, NA); usually on eastern slopes ca. 30 km walking distance NE from Hacienda Luisiana and the Apurimac River, 12°30'S, 073°30'W, 3400 m, 19 July 1968, Dudley 11221 (F!, USM!). Junín: Jauja, Dist. Molinos, Comunidad Curimarca, Jucha, 11°33'53"S, 075°18'58"W, 3893 m, 10 November 2016, Ames s.n (Z!). Satipo, Dist. de Pampa Hermosa, Comunidad de Toldopampa, Tasta, 11°26'08"S, 074°53'58"W, 3754 m, 04 October 2016, Ames s.n (Z!); Junin/Cusco Prov. Satipo/La Convención, Cordillera Vilcabamba. Río Ene, slope near summit of divide, 11°39'30"S, 073°40'02"W, 3350 m, 07 June 1997, Boyle 4151 (USM!). Puno: Limbani, Huancasayani, on road to Limbani just east of Abra Aricoma, 14°13'S, 069°42'W, 3750 m, 28 March 1987, Boertmann 129 (AAU!, QCA!); Huancasayani between Abra Aricoma and Limbani, 14°13'S, 069°42'W, 3750 m, 28 March 1987, Brandbyge 511 (AAU!).

Polylepis frontinensis T.Boza & M.Kessler, sp. nov.

Figs 31, 32

Diagnosis

This species differs from Polylepis quadrijuga Bitter (1911) in having obovate leaflets with shorter villous hairs and a lower number of stamens and from P. sericea Wedd. (1857) by obovate leaflets (versus elliptic leaflets), serrate leaflet margins (versus entire) and longer styles.

Figure 31. 

Polylepis frontinensis T.Boza & M.Kessler A flowers B flowering branch C upper leaflet surface D habit. Scale bars: 5 mm (A); 2 cm (B); 1 cm (C). Photographs by M. J. Sanin.

Type

Colombia. Antioqui: Urrao, Páramo Frontino, 06°30'N, 76°07'W, 3400 m, 5 Sep 2000, J.A. Perez & N. Parra 1477 (holotype: MEDEL!)

Figure 32. 

Polylepis frontinensis T.Boza & M.Kessler A flowering branch B stipular sheaths C upper leaf surface D lower leaf surface E fruits (A Alvarez 84 B–E Kessler 14777). Scale bars: 5 cm (A); 3 cm (C, D); 3 mm (E). Photographs by T. E. Boza E.

Description

Trees 4–8 m tall. Leaves only slightly congested at the ends of the branches, imparipinnate with 3–4(5) pairs or lateral leaflets, obtrullate in outline, (2.5–)3.3–5.2 × (1.8–)2.3–3.5 cm; rachises villous, point of leaflet attachment with a tuft of long, straight hairs, slightly resinous, stipular sheaths acute at the apex with spurs, densely sericeous on the outer surface; leaflets obovate in outline, second pair from the terminal leaflet the largest, one of this pair (1.1–)1.4–2.0 × 0.4–0.8 cm; margin serrate with 5–6 teeth, coriaceous, apically slightly emarginate, basally unequally cordate; upper leaf surfaces glabrous with few trichomes in the mid-vein depression; lower surfaces densely villous with hairs 1.4–1.8 mm. Inflorescences pendant, 6.3–10.6 cm long, bearing 7–15 flowers; floral bracts 4.5–5.4 mm long, narrowly triangular, sparsely villous on the outer surface; rachises sparsely villous. Flowers 7.5–8.2 mm diam.; sepals 3–4, ovate, densely villous outside; stamens 9–11; styles fimbriate, 2.8–3.2 mm long. Fruits turbinate, with variable number of spines, densely villous; 3.3–3.6 × 4.7–5.6 cm including spines. Diploid.

Distribution, habitat, and ecology

Polylepis frontinensis occurs in north-western Colombia in the Páramo Frontino, also called Páramo del Sol (Fig. 41). It grows at the upper limit of humid montane cloud forest at 2900–3680 m elevation. Polylepis frontinesis forms 4.9% (132.74 ha) of the total area of Polylepis forest identify for Colombia (Fadiño and Caro 2009, as P. quadrijuga). It occurs in small populations in a matrix of mixed forest dominated by species of the genera Escallonia, Hesperomeles, Myrsine and Weinmannia (Rangel-Ch and Arellano 2010). Some populations occur along streams, where they are mixed with Gynoxys baccharoides (Rangel-Ch and Arellano 2010).

Etymology

This species is named after the Páramo Frontino to which its distribution appears to be restricted.

Conservation status

Polylepis frontinensis is restricted to the upper humid montane cloud forest limit in the Páramo Frontino. Its estimated extent of occurrence (EOO) and area of occupancy (AOO) are 24 km2. The area of distribution of the species is largely unprotected, except for the private Reserva Colibrí del Sol which only includes a few hundred individuals of this species (M. Kessler, pers. obs.). In addition, there is evidence of clearance of Polylepis forests elsewhere in the páramo (Rangel-Ch and Arellano 2010). We assess the species as Critically Endangered (B2ac, C2a).

Notes

The populations of Polylepis from Páramo Frontino have previously been identified either as P. quadrijuga or P. sericea (e.g., Rangel-Ch and Arellano 2010, Fajardo-Gutierrez et al. 2018). Indeed, P. frontinensis resembles P. quadrijuga in having 3–4 lateral leaflet pairs and long inflorescences with numerous flowers. However, it has obovate leaflets with villous hairs 1.4–1.8 mm long, whereas P. quadrijuga has elliptic leaflets with tomentose hairs 0.7–0.9 mm long. Additionally, P. frontinensis is morphologically similar to P. lanuginosa and P. sericea with which it shares similar lower leaflet surface hair density and the number of stamens (13–15). The most obvious differences between P. frontinensis and these species is leaflet shape, with P. frontinensis having obovate leaflets, whereas the other two species have elliptic leaflets. Furthermore, P. frontinensis has longer styles (2.8–3.2 mm) than P. lanuginosa and P. sericea (1.9–2.5 mm). In P. lanuginosa, the hairs on the lower leaflet surfaces are yellowish and lanate, whereas in P. frontinensis they are whitish and villous. The three species can also be distinguished by the leaflet margins, with P. frontinensis having serrate margins, P. lanuginosa crenate margins and P. sericea entire margins.

Considering the morphological intermediacy of P. frontinensis with P. quadrijuga and P. sericea, we hypothesize that this species might be of hybridogenic origin between members of section Sericeae subsection Sericeae and section Reticulatae.

Specimens examined

Colombia. Antioquia: Urrao, Vereda El Chuscal, sector Alto de las campanas, hacia La Laguna Campanas, 06°27'46"N, 076°07'37"W, 3830 m, 20 June 2013, Alvarez 84 (HUA!, MO!); Páramo del Sol, Sector Alto del Burro, 3600 m, 17 April 2011, Alzate 4168 (HUA!); Chical, Reserva ProAves “Colibrí del Sol” Páramo frontino, 06°26'22"N, 076°05'47"W, 3300 m, 04 February 2015, Kessler 14772; 14773; 14774; 14775; 14776; 14777 (Z!); Páramo de Frontino, Llano Grande, 3460 m, 06 January 1984, Londoño 51 (HUA!,MEDEL); Páramo de Frontino, 06°30'N, 076°07'W, 3400 m, 05 September 2000, Perez & Parra 1477 (MEDEL); Páramo de Frontino, 3450 m, 22 September 1994, Renteria 10555 (HUA!); Páramo de Frontino, Zona situada entre el 15 y la Esperanza, 2980–3680 m, 18 May 1985, Renteria 4038 (HUA!); Páramo de Frontino, sitio Llano grande, 06°27'24"N, 076°07'22"W, 3380 m, 10 September 1986, Roldán 315 (COL!, MO!, HUA!); Páramo frontino. Camino de Puente Largo al cerro Cuchilla de Frontino, 06°30'N, 076°07'W, 3600–3800 m, 19 July 1995, Sánchez 2244 (COL!, MEDEL); Páramo de Frontino. Camino entre Puente Largo y Llano Grande, 06°30'N, 076°07'W, 3550–3600 m, 20 July 1995, Sánchez et al. 2289 (MEDEL); Páramo El Sol, Vereda La Encarnación, 06°29'12"N, 076°06'33"W, 3518 m, 24 May 2014, Sarrazola 699 (HUA!). Páramo Frontino, near Llano Grande, 3450 m, 26 October 1976, Boeke 235 (MEDEL, MO!).

Polylepis humboldtii T.Boza, K.Romoleroux & M.Kessler, Phytoxa 454(2): 113. 2020

Figs 33, 34

Type

Ecuador. Chimborazo: Lagunas de Atillo, 02°08'S, 78°34'W, 3465 m, 17 Dec 2019, K. Romoleroux, T.E. Boza E. & E. Bastidas 6199 (holotype: QCA!; isotype: Z!).

Figure 33. 

Polylepis humboldtii T.Boza, K. Romol. & M.Kessler A flowering branch B upper leaflet surface C lower leaflet surface D bark E flowers (A–E Romoleroux et al. 6199). Scale bars: 3 cm (A); 1 cm (B, C); 3 mm (E). Photographs A, D T. E. Boza E. B, C, E E. Bastidas.

Description

Trees 4–12 m tall. Leaves strongly congested at the branch tips, imparipinnate with 3–4 pairs of the lateral leaflets, obtrullate in outline, 4.5–6.3 × 3.4–4.3 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically acute with spurs, densely sericeous in the upper surface; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.8–2.8 × 0.6–0.9 cm; margin entire, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely sericeous with whitish hairs 0.2–0.4 mm. long. Inflorescences pendant, 13.0–17.9(–20.4) cm long, bearing 23–29 flowers; floral bracts 9.3–11.1 mm long, narrowly triangular, densely sericeous on the outer surface; rachises glabrous. Flowers 7.4–8.4 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 9–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.9–2.9 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 3.3–5.1 × 3.1–7.4 mm including spines. Diploid.

Figure 34. 

Polylepis humboldtii T.Boza, K.Romoleroux & M.Kessler A flowering branch B upper leaf surface C lower leaf surface D fruit E stipular sheats (A, D Carate 187 B Carate 185 C, E Carate 188). Scale bars: 7 cm (A); 2 cm (B, C); 5 mm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis humboldtii is restricted to Chimborazo Province in Ecuador (Fig. 41). It occurs in small populations in mixed Andean Forest at 3800–4000 m elevation.

Conservation status

The AOO is estimated as 4 km2 and it has been collected at only two locations in Ecuador. Although it is protected within Sangay National Park, burning of the páramo grassland matrix likely affects the remaining Polylepis forest patches. Therefore, we assess P. humboldtii as Critically Endangered (B2a, C2).

Notes

Polylepis humboldtii seems morphologically closest to P. sericea with which it shares similar leaflet shape, margin, apex and upper and lower leaflet surfaces hairs type and density. The most obvious differences between these species are leaflet hair length, with P. humboldtii having shorter hairs than P. sericea (0.2–0.4 mm versus 0.7–1.0 mm) and longer inflorescences (13.0–20.4 cm) with more flowers (23–29) than P. sericea (3.3–4.5 cm, 9–15 flowers). Additionally, P. humboldtii occurs in central Ecuadorean Andes, whereas P. sericea is distributed from western Venezuela to central Colombia.

Specimens examined

Ecuador. Chimborazo: Alausí, Achupallas, alrededores, 2°17'S, 78°39'W, 3300 m, 11 July 2013, Caranqui 2565 (QCA!); Lagunas de Atillo, 2°8'S, 78°34'W, 3465 m, 13 April 2009, Carate et al. 184; 185; 188 (QCA!).

Polylepis loxensis T.Boza, K.Romoleroux & M.Kessler, Phytoxa 454(2): 118. 2020.

Figs 35, 36

Type

Ecuador. Loja: Laguna Chinchilla, 03°36'20"S, 079°23'08"W, 3610 m, 21 Dec 2019, T.E. Boza E. & C. Medina 3185 (holotype: QCA!; isotypes: Z!, CUZ!).

Figure 35. 

Polylepis loxensis T.Boza, K. Romol. & M.Kessler A flowering branch B habit C upper leaflet surface D lower leaflet surface (A–D Boza & Medina 3185). Scale bars: 2 cm (A); 0.5 cm (C, D). Photographs by T. E. Boza E.

Description

Trees 4–10 m tall. Leaves strongly congested at the branch tips, imparipinnate with 3–4(–5) pairs of the lateral leaflets, obtrullate in outline, 2.6–3.6 × 2.1–3.2 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically truncate, densely sericeous in the upper surface; leaflets narrowly to broadly obovate in outline, second pair from the terminal leaflet the largest, one of this pair 1.2–1.6 × 0.5–0.8 cm; margin serrate at apex with 3–4 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous with few hairs on mid-depression; lower leaflet surfaces densely sericeous with whitish silky hairs 0.2–0.6 mm long. Inflorescences pendant, (3.5–)4.3–10.5(–12.2) cm long, bearing 9–27 flowers; floral bracts 5.5–6.3 mm long, narrowly triangular, densely sericeous on the outer surface; rachises densely sericeous. Flowers 4.4–5.2 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 7–9, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.7–2.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 1.7–3.0 × 1.4–1.5 mm including spines. Diploid.

Figure 36. 

Polylepis loxensis T.Boza, K.Romoleroux & M.Kessler A flowering branch B lower leaf surface C upper leaf surface D stipular sheaths (A, B Laegaard 19109 C Lewis 3804 D Jørgensen 2228). Scale bars: 5 cm (A); 2 cm (B, C). Photographs by E. G. Urquiaga F.

Distribution, habitat and ecology

Polylepis loxensis is restricted to south-western Ecuador (Fig. 41). It has been collected in southern Azuay Province (Nabon) and at Laguna Chinchilla and Fierro Urco in northwest Loja Province bordering with El Oro Province. The páramos in this region are part of the physiographic unit called ‘Páramos del Sur’ of the Western Cordillera or Ecuador. The species occurs in the humid páramo at 2650–3700 m elevation, where it grows in mixed forest with Gynoxis cuicochensis, Brachyotum ledifolium and Weinmannia glabra (Lassermann 2009). In this region, a new, endemic species of hummingbird has recently been discovered (Sornoza-Molina et al. 2018), which together with this new Polylepis species suggests that this mountain region may be a center of endemism.

Conservation status

Polylepis loxensis is known from six locations with an EOO of 728 km2 and an estimated AOO of 32 km2. No conservation actions have been taken to date. The area is heavily grazed by cattle and horses, pine plantations occupy large extensions and a large proportion of the area is under gold mining concessions (Sornoza-Molina et al. 2018). Based on its restricted distribution, fragmented and degraded habitat with low populations size and lack of habitat protection, we assess P. loxensis as Critically Endangered (A2a, B1a+B2a, C2a).

Notes

Polylepis loxensis is most similar to P. ochreata, with which it shares the emarginate leaflet apices and subcordate leaflet bases and similar dense, short, white silky hair on the lower leaflet surfaces. Indeed, they were treated as conspecific by Boza Espinoza et al. (2019), but later, Boza Espinoza et al. (2020a) recognized their morphological and ecological distinctness. The two species differ in number of leaflet pairs, with P. loxensis having 3–4(–5) and P. ochreata 4–7. Polylepis loxensis further has shorter inflorescences (3.5–12.2 cm) bearing 9–27 flowers, fewer stamens (7–9) and shorter styles (1.7–2.0 mm), whereas P. ochreata has longer inflorescences (8.1–17.4 cm) bearing 21–49 flowers, more stamens (9–15) and longer styles (2.1–2.6 mm).

Specimens examined

Ecuador. Azuay: Nabón, 3°28'20"S, 79°02'24"W, 2800–3300 m, 15 November 2008, Salgado 1419 (LOJA!); Loja: Loja, Fierro Urco, 03°36'20"S, 079°23'08"W, 3610 m, 19 December 2019, Boza & Medina 3184 (QCA!, Z!, CUZ!); Fierro Urco, Saraguro-Loja, km 12.4 turnoff towards Fierro Urco, km 23.8, 03°43'10"S, 079°19'18"W, 3840 m, 6 December 1994, Jørgensen et al. 1240 (AAU!, LOJA!, MO!); road San Lucas–Saraguro, km 9, turn off to Fierro Urco, 11 km to the pass, 03°43'03"S, 079°19'25"W, 3630 m, 4 November 2000, Jørgensen et al. 2228 (QCA!); ca. 10 km along road to Fierro Urco, 03°41'S, 079°01'W, 2850 m, 8 September 1998, Laegaard 19109 (AAU!, LOJA!, QCA!); Fierro Urco, grass Páramo 12 km to the left (northbound) from the Panamericana highway, 03°43'S, 079°19'W, 3600–3650 m, 9 June 1999, Sklenár & Laegaard 7096 (AAU!, GOET!); ca. km 12 along Páramo road to Fierro Urco, 03°41'S, 079°01'W, 3650 m elev., 9 June 1999, Laegaard & Sklenár 20279 (AAU!, LOJA!, QCA!); Páramo of Fierro Urco SW of Saraguro, 03°43'S, 079°19'W, 3500 m elev., 21 November 1996, Lewis et al. 2121 (AAU!); road Loja-Cuenca, km 50, track to Fierro Urco, km 5–7, 03°41'S, 079°17'W, 3150–3350 m elev., 25 October 1996, Lewis & Lozano2724 (AAU!,LOJA!, MO!, QCA!); road Loja-Saraguro, km 52, track to Fierro Urco, km 10, 03°42'S, 079°18'W, 3350–3450 m elev., 17 January 1997, Lewis et al. 2932 (AAU!, LOJA!, MO!); road Loja–Saraguro, 8.5 km N of San Lucas, track to Fierro Urco, km 11, 03°43'10"S, 079°19'18"W, 3550 m elev., 15 January 1998, Lewis & Hughes 3804 (AAU!, LOJA!, MO!, QCA!); Fierro Urco, 03°41'S, 079°22'W, 3700 m elev., 11 January 1995, P. Lozano 172 (LOJA!); Saraguro, Laguna Chinchilla, 03°36'20"S, 079°23'08"W, 3610 m elev., 21 December 2019, Boza & Medina 3186 (QCA!, Z!, CUZ!), cerro Chinchilla, parroquía Celén, 03°35'44"S, 079°20'17"W, 3000 m elev., 19 September 1984, Jaramillo 7332 (QCA!), 7335 (GB, QCA!); Laguna Chinchilla, 03°36'17"S, 079°23'49"W, 11 November 2008, Salgado et al. 1392; 1394 (LOJA!).

Polylepis ochreata (Wedd.) Bitter, Bot. Jahrb. Syst. 45: 597–598. 1911.

Figs 37, 38

Polylepis ochreata var. integra Bitter, Bot. Jahrb. Syst. 45: 598, fig. 4. 1911. Type. Ecuador. Imbabura: Volcan Mojanda, Mar. 1901, Sodiro s.n. (holotype: FI n.v.; isotype: GOET!).

Polylepis subintegra Benoist, Bull. Soc. Bot. France 81: 326. 1934. Type. Ecuador. Pichincha: W slopes of Cerro Pichincha, Taurichupa, 4000 m, 28 Nov 1930, Benoist 3356 (holotype: P!).

Basionym

Acaena ochreata Wedd., Chlor. And. 2: 240. 1855.

Type

Ecuador. Pichincha: W slopes of Cerro Pichincha, 3600 m, May 1856, Jameson 73 (lectotype, designated by Simpson 1979, pg. 28: P; isolectotypes: A!, G!, GH!, US!; photos at F!, MO!, US!).

Figure 37. 

Polylepis ochreata (Wedd.) Bitter A inflorescence B fruits C stipular sheaths D lower leaflet surface E flowering branch F upper leaflet surface G juvenile leaves. Scale bars: 5 mm (A, B); 3 mm (C); 1 cm (D, F, G); 3 cm (E). Photographs by T. E. Boza E.

Description

Trees 2–10 m tall. Leaves strongly congested at the branch tips, imparipinnate with 4–7 pairs of the lateral leaflets, obtrullate in outline, (3.9–)4.4–7.0 × 2.9–4.7 cm; rachises glabrous to densely sericeous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically acute, glabrous to sparsely sericeous (adult) or densely sericeous (juvenile) in the upper surface; leaflets narrowly elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.6–3.0 × 0.5–0.7 cm; margin entire to slightly serrate with 4–6 teeth, coriaceous, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely sericeous with whitish silky hairs 1.3–2.0 mm long in juvenile plants and 0.3–0.5 mm long in adult plants. Inflorescences pendant, 8.1–15.5(–17.4) cm long, bearing (21–)26–49 flowers; floral bracts 5.9–12.8 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 6.6–9.0 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 9–13, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.1–2.6 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 4.7–7.5 × 6.1–7.9 mm including spines. Diploid, tetraploid and hexaploid.

Figure 38. 

Polylepis ochreata (Wedd.) Bitter A flowering branch B fruit C lower leaf surface D upper leaf surface E stipular sheaths F young leaves (A Romoleroux 350 B Laegaard 55665 C Romoleroux 5413 D Romoleroux 300 E Clark 5820 F Ericksen 59086). Scale bars: 6 cm (A); 6 mm (B); 4 cm (C, D). Photographs by E. G. Urquiaga F.

Distribution habitat and ecology

Polylepis ochreata is distributed in the Andes of Ecuador and in Nariño, southernmost Colombia (Fig. 41). It occurs at 2950–4350 m elevation in humid montane forest habitats. In northernmost Ecuador, P. ochreata often co-occurs with P. longipilosa, with which it hybridizes (Romoleroux 1996). These species have quite similar morphological characters which has complicated the taxonomic classification, mainly in the Province of Carchi, where they occur in sympatry. Polylepis ochreata occurs in mixed population with other woody species, such as Brachyotum ledifolium and Miconia latifolia (Salgado 2008). Pollen viability of P. ochreata has been measured as 60% (Caiza et al. 2018). In Colombia, the forest remnants of P. ochreata harbor the Polylepis specialist bird species Conirostrum binghami (= Oreomanes fraseri) (Valderrama and Verhelst 2007).

Conservation status

The EOO is estimated at 7,525 km2 and AOO at 112 km2. The species is known from 16 locations. In Colombia, remnants of P. ochreata forests are under pressure by the expansion of potato cropland, so that the Cumbal population has been assessed as EN and Chile’s population as VU (Rangel-Ch and Arellano 2007, as P. sericea). In Ecuador, P. ochreata is protected within the El Angel Ecological Reserve in Carchi and Yanacocha Reserve in Pichincha, where it is also subject to reforestation activities. Nevertheless, based on its restricted and fragmented distribution and continuing population losses, we assess P. ochreata as Vulnerable (B1a+B2a, C1).

Notes

Described by Bitter in 1911, this species was synonymized under P. sericea by Simpson (1979), a course of action followed by Romoleroux (1996). It was re-instated at species level by Boza Espinoza et al. (2019) based on its distinctive morphology characters, including having four or more leaflet pairs, glabrous to sparsely sericeous leaf rachises and leaflet margins, short (0.3–0.5 mm long), evenly distributed hairs on the lower leaflet surfaces and 21–43 flowers per inflorescence. Polylepis ochreata is most similar to P. albicans and P. argentea, with which it shares the elliptic leaflet shape and subcordate bases of the leaflets. However, the three species differ in number of lateral leaflet pairs, with P. ochreata having 4–7 pairs, P. albicans 3–4 and P. argentea 2. Polylepis ochreata has (21)26–49 flowers per inflorescence, whereas P. albicans has 18–21 and P. argentea 5–6(–9).

Boza Espinoza et al. (2019) considered that P. ochreata is the only member of the sericea complex in Ecuador. However, K. Romoleroux recognized further variation in the country, resulting in the separation of both P. humboldtii and P. loxensis from P. ochreata by Boza Espinoza et al. (2020a).

Specimens examined

Ecuador. Bolívar: Guaranda, Parroquia Salinas, recorrido entre los Arrayanes y Pambabuela, 01°22'06"S, 079°03'47"W, 3615 m, 10 Febrero 2005, Vargas López 4696 (AAU!, K, MO!, QCNE, US!). Carchi: Cumbal, 00°48'19"N, 077°53'03"W, 3500 m, Bensman 418 (MO!, WIS); Km 31 west of Tulcán on road to Maldonado, 00°52'N, 077°55'W, 3900 m, 21 June 1984, Todzia 2485 (MO!). La Libertad (Alizo), 00°45'N, 077°59'W, Asplund 17037 (S); Páramos de El Angel S of Volcán Chiles, 00°45'N, 077°58'W, 3850 m, 14 March 1985, Eriksen 59086 (AAU!, MO!). Maldonado, Volcán Los Chiles, along road 9 km W of Tufiño, 00°49'N, 077°57'W, 3500 m, 10 March 1992, Lægaard 101661 (AAU!, GOET, QCA!); Tufiño, Road Tulcán-Maldonado, near Volcán Chiles, 00°48'N, 077°56'W, 3850–4000 m, 16 August 1985, Lægaard 54966 (AAU!, MO!, QCA!); S slopes of volcán Chiles, 14–16 km W of Tufiño on road to Maldonado, 0–1 km S of the road, 00°47'N, 077°57'W, 3850–3900 m, 18 January 1988, Molau 2536 (AAU!, GB, MO!, QCA!); a 33 km de Tulcán, 00°48'N, 077°54'W, 3900 m, Romoleroux 173 (AAU!, QCA!); Carretera Tulcán-Tufiño-Maldonado, 00°47'N, 077°57'W, 3800–3900 m, 12 October 1986, Romoleroux 189 (AAU!, QCA!); Tulcán, 33.4 km W of Tulcán on road to Maldonado, Páramo de Chilos on Colombia border, 00°48'19"N, 077°53'03"W, 3900 m, 22 September 1979, Gentry 26342 (AAU!, MO!, QCA!). Cotopaxi: Toacaso, Quebrada Faldiguera, 00°41'S, 078°45'W, 3750 m, 16 February 1991, Jørgensen 93000 (AAU!, MO!, QCA!). Imbabura: Gonzalez Suarez, Laguna Mojanda, camino, forêt d’altitude, 00°08'N, 078°15'W, 2500 m, 01 February 1996, Billiet 6762 (BR, MO!). La Merced de Buenos Aires: at road Chauasqui–Merced de Buenos Aires, km 20, near pass, 00°33'N, 078°17'W, 3700–3850 m, 10 December 1984, Lægaard 53475 (AAU!, MO!, QCA!). Otavalo: forested path to Laguna Mojanda (La via antigua a Mojanda por el cementerio), 00°10'00"N, 078°15'00"W, 3800 m, 31 December 2000, Clark 5820 (QCA!, US). San Rafael, W slopes of Volcán Cayambe, 00°10'00"N, 078°15'00"W, 3700–3900 m, 27 July 1967, Sparre 17789 (AAU!, S). Napo: Nono, N-side of Volcán Pichincha above Hacienda Yanacocha, 00°07'S, 078°34'W, 3950–4050 m, 02 June 1985, Lægaard 54457 (AAU!, MO!, QCA!). Pichincha: along, Northern slopes of Cerro Corazón, 2–4 km W along on the road to Hacienda El Pongo, 00°28'S, 078°36'W, 3100–3200 m, 13 May 1979, Holm-Nielsen 18007 (AAU!, MO!); Corazón, 00°31'53"S, 078°39'36"W, 3260 m, Sodiro s.n. (AAU!); Lloa, Volcán Atacazo, W slope, 17 km from San Juan, 00°20'S, 078°38'W, 2850 m, 25 August 1980, Holm-Nielsen 25115 (AAU!); 25148 (AAU!); Volcán Atacazo, SW slope, km 19 from San Juan, 00°21'S, 078°39'W, 2900 m, 25 August 1980, Holm-Nielsen 25169 (AAU!); West-side of Volcán Atacazo, along drinkwater canal, 00°20'S, 078°38'W, 3700–3750 m, 11 August 1984, Lægaard 52639 (AAU!, MO!, QCA!); 52641 (AAU!); along drinkwater-canal on W-side of Atacazo, ca. 5 km S of Campamento, 00°20'S, 078°38'W, 3700–3800 m, 24 October 1984, Lægaard 53256 (AAU!); along drinkwater-canal on W-side of Atacazo, ca. 5 km S of Camparmento, 00°20'S, 078°38'W, 3750 m, 28 October 1984, Lægaard 53259 (AAU!); 53260 (AAU!); along drinkwater-canal on W-side of Volcan Atacazo, 00°20'S, 078°38'W, 3200 m, 24 November 1985, Lægaard 55665 (AAU!, GOET, MO!, QCA!); Volcán Atacatzo, 00°20'S, 078°37'W, 3500 m, Mille 364 (US); carretera Quito–San Juan–San José de la Victoria, 00°17'53"S, 078°38'20"W, 2900–3400 m, 24 December 1987, Zak 3265 (AAU!, GB, MO!); Nono, Camino Yanacocha NW of Volcan Pichincha, 00°05'S, 078°33'W, 3200–3800 m, 03 October 1981, Balslev 2049 (AAU!, MO!, NY, QCA!); 28 November 1930, Benoist 3356 (P); Yanococha, faldas noroccidentales, 00°07'S, 078°35'W, 22 March 1987, Jaramillo Asanza 9573 (AAU!, NY, QCA!); 9588 (AAU!, QCA!); N-side of Volcán Pichincha above Hacienda Yanacocha, 00°07'S, 078°34'W, 3800 m, 04 June 1985, Lægaard 54458 (AAU!, MO!); 54459 (AAU!); 54462 (AAU!, QCA!); 54463; 54467 (AAU!, MO!); 54474; 54476; 54477 (AAU!, MO!, QCA!); Carretera Quito-Nanegalito-Santa Ana del Tablón, desvío Hda Yanacocha km 1–10 desde el desvío, 00°07'S, 078°34'W, 3500–3600 m, 06 December 1992, Romoleroux 1495A (AAU!); Yanacocha, 3617 m, 28 November 2008, Romoleroux 5342 (QCA!); Yanacocha, sector La Despensa, 00°07'52"S, 078°35'06"W, 3837 m, 14 Febrero 2009, Romoleroux 5413 (MO!, QCA!); Reserva Yanacocha, Trocha “Inca” 1–600 m, 00°06'44"S, 078°34'24"W, 3536 m, 11 June 2011, Ulloa Ulloa 2171 (MO!, QCA!); carretera Quito-Nono-Tandayapa, desviación a Yanacocha en la localidad de Guanto-Pugro, en la hacienda “Alto Perú”, estribaciones N.O. del Volcán Pichincha, 00°05'S, 078°35'W, 3200–3300 m, 17 November 1987, Zak 2946 (AAU!, GB, MO!); Quito, SW-slopes of volcan Atacazo, 00°20'S, 078°35'W, 3650 m, 11 October 1984, Brandbyge 42817 (AAU!, MO!, QCA!); SW-slopes of volcán Atacazo, 00°20'S, 078°35'W, 3700–3800 m, 28 October 1984, Brandbyge 42837 (AAU!, MO!, QCA!); Volcán Pichincha, N slopes, road to Hda. Yanacocha from pass on Quito-Nono road, km 7–11.2, 00°07'S, 078°33'W, 3600–3500 m, 12 October 1991, Øllgaard 99187 (AAU!); Carretera a San Juan-Atacazo, km 1–12, 00°20'S, 078°35'W, 3700–4000 m, 02 September 1990, Romoleroux 1060 (AAU!, QCA!); Tocachi, 00°08'N, 078°16'W, 3260 m, Asplund 17103 (S); 00°08'N, 078°16'W, Benoist 4549 (S); NW side of Pichincha, 00°08'N, 078°16'W, Fagerlind s.n (S); 00°08'N, 078°16'W, Holmgren 664 (S); 00°08'N, 078°16'W, Jameson s.n (MO!); Páramo de Mojanda, at Laguna Negra and S-side of Laguna Grande, 00°08'N, 078°16'W, 3800 m, 14 May 1985, Lægaard 54316A (AAU!, QCA!); 00°08'N, 078°16'W, Romoleroux 1495 (AAU!, QCA!); 243 (QCA!); 245 (NY, QCA!); 305 (QCA!); 00°08'N, 078°16'W, 3700 m, Romoleroux 350 (QCA!).

Polylepis sericea Wedd., Chlor. Andina 2: 238. 1857.

Figs 39, 40

Polylepis hypargyrea Bitter, Bot. Jahrb. Syst. 45: 600. 1911. Type. Venezuela. Páramo de la Culata, Sierra Nevada Moritz 1120 (holotype: B destroyed; isotypes: BM!; photos at F!, GH!).

Polylepis quindiensis Cuatrecasas, Revista Acad. Colomb. Ci. Exact. 4: 343 .1941. Type. Colombia. Caldas: Cordillera Central, W of Macizo del Quindio, Nevado del Ruiz, 3400–3500 m, 5 May 1940, Cuatrecasas 9327 (holotype: COL!; isotypes: BC!,US!).

Type

Venezuela. Mérida: Sierra Nevada, 3500 m, Jun 1847, Funck & Schlim 1546 (lectotype, designated by Simpson 1979, pg. 28: P!; isolectotypes: G!; phot at F!).

Figure 39. 

Polylepis sericea Wedd A inflorescence B flowers C leaves D flowering branch E bark. Scale bars: 5 mm (A); 2 mm (B); 1 cm (C, D). Photographs by A. Möhl.

Description

Trees 3–7(12) m tall. Leaves strongly congested at the branch tips, imparipinnate with 2–3(–4) pairs of lateral leaflets, obtrullate in outline, 3.9–4.2 × 2.5–3.8 cm; rachises glabrous, points of leaflet attachment with a tuft of long, straight whitish hairs; stipular sheaths apically acute with spurs, almost glabrous with some hairs at the edges on the outer surfaces and glabrous in the inner surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.8–2.1 × 0.8–1.0 cm; margin entire, coriaceous, apically emarginate to retuse, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely sericeous with whitish hairs 0.7–1.0 mm long. Inflorescences pendant, 3.3–4.5 cm long, bearing 9–15 flowers; floral bracts 4.1–6.4 mm long, narrowly triangular, densely sericeous on the outer surface; rachises sericeous. Flowers 4.2–8.1 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 13–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.9–2.5 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely sericeous; 4.0–7.4 × 3.4–9.6 mm including spines. Diploid.

Figure 40. 

Polylepis sericea Wedd A flowering branch B lower leaf surface C upper leaf surface D stipular sheaths E fruit (A, B Aristeguieta 7886 C, D Berry 3812 E Schwabe 1987). Scale bars: 2 cm (A–C); 5 mm (E). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis sericea is found in two distinct geographic areas, the Cordillera de Mérida in the Andes of western Venezuela and the Cordillera Central of Colombia in Caldas, Quindio and Risaralda Departments (Fig. 41). It grows at 2800–4300 m elevation in humid montane forest, where it is the only species of the genus. In Venezuela, P. sericea mostly grows as homogeneous forest and sometimes mixed with Hesperomeles glabrata and H. pernettyoides (Arnal 1983). In Colombia, it represents 61.9% (1893.07 ha) of the total Polylepis forest estimated for this country (Fadiño and Caro 2009). In the Cordillera Central, it grows mixed with Myrsine parvifolia, Miconia salicifolia and Gynoxys baccharoides (Rangel-Ch and Arellano 2007). This species has been subject to detailed ecological and ecophysiological studies in Venezuela which, among other aspects, revealed that the net photosynthesis is highest at leaf temperatures of 13 °C, but is still 80% of this maximum at 3 °C and that it has high concentrations of carbohydrates in its leaves that allow supercooling down to -9 °C (Rada et al. 1985, 1996, 2009; Goldstein et al. 1994). Leaf anatomy changes with elevation to account for lower temperatures and increasing water stress at high elevations (Colmenares-Arteaga et al. 2005). As in many species of the genus, natural regeneration is highest along forest margins and in open forests, where shading is low enough to allow for seedling growth, but where herb cover is too low to outcompete them (Rada et al. 2011).

Figure 41. 

Geographical distribution of the species of subsection Sericeae.

Conservation status

The estimated Extent of Occurrence (EOO) for Polylepis sericea is 36,560 km2. The Area of Occupancy (AOO) is 100 km2. The species is known from 16 locations. It is protected in Venezuela within the Sierra Nevada and Sierra de la Culata National Parks, with some minor relicts in the highest areas of the Trujillo State, where more than 50% of the remnant forest of P. sericea are conserved (Arnal 1983). In Colombia, forest remnants of P. sericea are protected within Los Nevados National Park. We assess P. sericea as Vulnerable (B1a+B2a).

Notes

In her seminal taxonomic revision of the genus Polylepis, Simpson (1979) adopted a broad species concept of P. sericea, with the result that it was long considered the most widespread species of the genus. However, Boza Espinoza et al. (2019) subdivided the species into five morphologically, geographically and ecologically different species, namely P. albicans, P. argentea, P. canoi, P. ochreata and P. sericea. This treatment is also supported by the fact that, in Peru, two of these species (P. argentea and P. canoi) co-occur in mixed forests without interbreeding (Boyle 2001). Later, Boza Espinoza et al. (2020a) further separated P. humboldtii and P. loxensis from P. ochreata, resulting in the current recognition of seven species within what Simpson (1979) recognized as the single species P. sericea.

As defined by Boza Espinoza et al. (2019) and here, P. sericea can be distinguished from the most similar species P. ochreata by the number of leaflet pairs (2–3(–4) versus 4–7), leaflet margin (entire versus entire to slightly serrate), leaflet hair length (0.7–1.0 mm versus 0.3–0.5 mm), inflorescence length (3.3–4.5 cm versus 8.1–17.4 cm) and flower number (9–15 versus 21–49).

Specimens examined

Colombia. Caldas: Pereira, El Cisne, Laguna del Otúm, 04°46'N, 075°25'W, 3900–4200 m, 20 March 2009, Vargas 20063 (COL!). Villamaría, Cordillera central, vertiente occidental; cabeceras del río Otún, Laguna del Mosquito y plan del Villar, 04°58'N, 075°21'W, 3650–3750 m, 26 November 1946, Cuatrecasas 23257 (COL!); Cordillera Central, vertiente occidental, vert. sudoeste del Ruiz, El Prisco, páramos, 04°58'N, 075°22'W, 3500–3600 m, 05 May 1940, Cuatrecasas 9327 (COL!). Quindío: Salento, Vereda Cocóra; below Nevado del Quindio, 3800 m, 20–22 May 1989, Luteyn 12974 (MO!). Risaralda: Pereira, Cordillera central, en el paso de la Laguna del Otúm hacia la Quebrada Africa, 04°47'N, 075°24'W, 4300 m, 09 February 1980, Jaramillo 6276 (COL!).

Venezuela. Lara: Morán, Páramo del Jabon (Vertiente Oriental), 09°34'N, 070°06'W, 3100–3400 m, 02 November 1969, Cuatrecasas 28216 (MERF); Páramo Jabón, camino al páramo Cendé, 09°34'N, 070°06'W, 3000–3200 m, 30 December 1999, Riina 1036 (VEN). Mérida: Caracciolo Parra Olmedo, Páramo La Culata en quebrada, 08°46'43"N, 071°03'04"W, 3581 m, 07 October 2006, Bonifacino 2541 (VEN). Justo Briceño, Páramos de Laguna Grande, 08°48'N, 070°56'W, 21 January 1929, Pittier 13253 (MO!, VEN). Libertador, Parque Nacional Sierra Nevada. Loma Redonda Teleferico station and south, 08°33'N, 071°05'W, 4068 m, 20 May 1988, Dorr 5220 (AAU!); Pico Bolivar, 08°33'N, 071°02'W, 4200 m, 17 January 1968, Walter 443 (GOET!). Miranda, carretera hacia Piñango, Páramo Piedras Blancas, Dtto. Rangel, 09°00'N, 070°50'W, 3700 m, 03 March 1982, Aymard 1050 (MO!); Dist. Justo Briceño. Páramo y chirivital en la vertiente NW del Alto del Totumo, hoya del Río Chirurí, a 19.5 km de El Aguila por la carretera a Piñango, 08°51'N, 070°49'W, 3900–4000 m, 02 April 1982, Berry 3812 (MO!); 3844 (MO!, VEN); de El Aguila a Piñango, 08°56'24"N, 070°50'47"W, 3820 m, 03 August 2010, Grande 2565 (VEN). Pueblo Llano, Andes de Merida/Steilhang oberhalb Laguna Negra, 08°56'N, 070°41'W, 3500–3700 m, 01 August 1958, Schwabe s.n (GOET!); Andes de Merida, 08°56'N, 070°41'W, 4000 m, 01 January 1973, Schwabe s.n (GOET!). Rangel, Margenes del Río Chama, cerca de Apartadevos, 08°47'N, 070°51'W, 01 July 1971, Aristeguieta 7886 (MO!); Quebrada de la Mucuchache, SE de la entrada, 3600 m, 16 June 1981, Briceño 298 (VEN); Dist. Rangel, cascada SE of Laguna de Mucubaji and below Pico Mucuñuque, Parque Nacional Sierra Nevada, 08°48'N, 070°49'W, 3600–3800 m, 15 June 1988, Dorr 5524 (MO!, VEN); Sierra Nevada, 08°36'N, 070°53'W, 3800 m, 20 July 1934, Farenholtz 1833 (GOET!); Sierra Nevada, 08°36'N, 070°53'W, 4000 m, 27 July 1934, Farenholtz 1927 (GOET!); Quebrada Yoyo, 08°43'N, 070°49'W, 3880 m, 12 April 1930, Gehriger 73 (MO!, VEN); Distr. Rangel. Sierra Nevada de Santo Domingo, road between Laguna de Mucubaji and Laguna Negra, 08°47'N, 070°48'W, 3400 m, 03 July 1979, Kieft 87 (MO!, VEN); moraine at the head of the valley above L. Mucubají, on a small rocky cliff just above and east of the lowest falls, 08°47'N, 070°49'W, 3650 m, 21 July 1972, Loveless 1722 (MO!); Sierra Nevada, 08°36'N, 070°53'W, s.d., Moritz 1120 (MO!); La Nevada, 08°36'N, 070°53'W, 3352 m, 21 December 1904, Schlim 1546 (MO!); Berghange oberhalb Laguna Negra/Páramo, 08°46'N, 070°48'W, 3700 m, s.d., Schwabe s.n (GOET!); Páramo de Mucubají, Páramo vegetation around Cascadas along the trail to Laguna Negra Páramo, 08°46'49"N, 070°49'16"W, 3640 m, 12 October 2007, Sklenar 10240 (VEN); Caserio Mifafi, camino quebrada de río Chama-Caserio Mucumpis a través del páramo Piedra Blanca (entrada por la carretera Apartaderous-Pico Aguila), 08°48'N, 070°50'W, 14 August 1980, Stergios 2116 (MO!); Páramo seco y húmedo en el sector de Sto. Domingo de Mucubají los alrededores de la Laguna de Mucubají, 08°46'N, 070°49'W, 29 May 1986, Stergios 8378 (MO!). Santos Marquina, Sierra Nevada. Páramo alrededores de la Laguna Verde proximo Picos Humboldt y Bonpland, near edge of la LagunaVerde, 08°34'N, 070°59'W, 4000 m, 04 December 1959, Barclay 10034 (MO!); Cerro de Caballo, 08°32'N, 070°54'W, 3600–3850 m, 25 November 1959, Barclay 9816 (MO!); Sierra Nevada; alrededores de la Laguna Coromoto. Trail to Laguna Verde, 08°34'N, 071°00'W, 3300–3500 m, 03 December 1959, Barclay 9951 (MO!), Parque Nacional Sierra Nevada, Mérida, Páramo Media Luna, 300 m Westl der Teleferico-Station Loma Redonda, 3920 m, 10 January 1995, Berg 517 (VEN); Páramo del Aguila, 10 March 1951, Croizat 66 (VEN); alrededores inmediatos de la Laguna Brava (Páramo de la Laguna Brava), sector del Páramo de los Granates, Sierra de Santo Domingo, Cordillera de los Andes, 3300 m, 20 May 1971, López-Figueiras 8728 (VEN); Páramo, Los Colorados, 3900 m, 01 May 1988, López del Pozo 416 (VEN); Páramo, 3550 m, July 1988, López del Pozo 944 (VEN); Parque Nacional Sierra Nevada, Laguna Negra, 17 September 1998, Ramirez 5533 (VEN); Laguna Mucubají, above Los Apartaderos, 3625–3655 m, 21 July 1944, Steyermark 57513 (VEN); Laguna Negra, 3520 m, 18 May 1952, Varechi 962 (VEN). Tachira: Jauregui, Páramo Sumusica along the trail heading northwest from the mountain pass (road La Grita-San Jose de Bolivar), 08°01'31"N, 071°57'53"W, 3340 m, 17 October 2007, Sklenar 10356 (VEN). Trujillo: Boconó, Mun. Carache, P.N. Dinira, arriba de Mesa Arriba, debajo del Pico Cendé, ladera SO, 09°32'N, 070°07'W, 3200 m, 01 April 1999, Duno de Stefano 767 (MO!, VEN).

Pepea T.Boza & M.Kessler, sect. nov.

Diagnosis

Shrubs or trees, 1–2 lateral leaflet pairs; lower leaflet surfaces lanate or sericeous; fruit slightly twisted with short spines, densely sericeous.

Type

Polylepis pepei B.B. Simpson.

Note

The subsectional epithet Pepea is a noun in apposition.

Polylepis pepei B.B. Simpson, Smithsonian Contr. Bot. 43: 32. 1979.

Figs 42, 43

Type

Bolivia. Cochabamba: 77 km after Chapare on the road to Todos Santos, 4200 m, 4 Jan 1968, Vuilleumier 465 (holotype: US!; isotypes: MO!, NY!, P!, TEX!,US!, VEN!).

Figure 42. 

Polylepis pepei B.B. Simpson. A flowering branch B leaves C upper leaf surface D habit E bark. Scale bars: 1 cm (A, C); 2 cm (B). Photographs A–C, E A. Fuentes D J. Quisbert.

Description

Shrubs or trees 2–7(9) m tall. Leaves strongly congested at the branch tips, imparipinnate with 2 pairs of leaflets, obtrullate in outline, (1.3–)1.7–2.6 × 1.2–2.0 cm; rachises densely sericeous, points of leaflet attachment with a tuft of long; stipular sheaths apically truncate or with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 0.8–1.3 × 0.2–0.7 cm; margin entire, apically emarginate or tridentate due to a projection of the mid-vein, basally unequally cordate; upper leaflet surfaces sparsely to densely sericeous; lower leaflet surfaces densely sericeous with whitish hairs 0.6–0.9 mm long. Inflorescences upright, 1.2–1.6(–3.5) cm long, bearing 3 flowers; floral bracts 4.0–7.3 mm long, narrowly triangular, densely sericeous on the outer surface; rachises densely sericeous. Flowers 4.9–5.9 mm diam.; sepals 3–4, ovate, green, densely sericeous outside; stamens 5–9, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 3.0–4.9 mm long. Fruits turbinate often slightly twisted, with variable numbers and placement of short spines, densely sericeous; 2.3–5.7 × 1.9–3.9 mm including spines. Diploid.

Figure 43. 

Polylepis pepei B.B. Simpson A flowering branch B stipular sheaths C upper leaf surface D flower E fruit F lower leaves surface (A, C–E Kessler 3386 F Beck 14680 D Beck 11859). Scale bars: 2 cm (A); 1.5 cm (B, C); 6 mm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis pepei has been found in northern to central Bolivia and southern Puno (Peru) where it has been collected at one locality in San Antonio de Putina Province close to the border with Bolivia (Fig. 24). It grows at 3550–4800 m elevation, where it typically forms the uppermost forests, often in isolated patches high above the closed treeline, often on rocky slopes (Sylvester et al. 2017). Forest remnants in sites that are topographically inaccessible to grazing animals and man-made fires support a unique flora with many previously undescribed species (Sylvester et al. 2016) that presumably represents remnants of the natural potential vegetation (Sylvester et al. 2014a). Such inaccessible forest remnants are also characterized by a high proportion (on average 30%) of dead, standing trees, which support a diverse flora of epiphytic bryophytes and lichens (Sylvester et al. 2017). In accessible forests, such dead trees are harvested by the local inhabitants as firewood (Toivonen et al. 2018). The world’s highest vascular epiphytes (Melpomene spp., Polypodiaceae) have been found at elevations of up to 4550 m in forest of P. pepei (Sylvester et al. 2014b). These forests also support the hemiparasite Tristerix longebracteatus (Desr.) Barlow & Wiens (Loranthaceae) at over 4600 m elevation (Sylvester et al. 2014b). Stands of P. pepei are often very dense, with numerous trunks of relatively small diameters of around 10 cm (Toivonen et al. 2018). Radial tree growth of the species is enhanced by rains in the dry season and varies depending on local conditions including slope and substrate (Jomelli et al. 2012). Vegetative reproduction increases with elevation, to the degree that the uppermost stands have no reproduction by seeds at all (Hertel and Wesche 2008; Toivonen et al. 2018).

Conservation status

Polylepis pepei is known from 12 locations with an EOO of 35,111 km2 and an estimated AOO of 68 km2. Polylepis pepei was categorized as VU (A1c) in the World List of Threatened Trees (Oldfield et al. 1998). Later, it was classified as EN (B1b(i,iii)) in the Red List of Threatened Flora of Bolivia (Arrázola and Coronado 2012). It is protected within Madidi and Carrasco National Parks of Bolivia. A stand above Unduavi has been focus of conservation attention due to the presence of the critically endangered bird species Anairetes alpinus (Navarro et al. 2010). Stands of P. pepei are severely threatened by livestock activities that involve annual burns of the grasslands that often extend into the forests. This species survives low to moderate levels of direct use by local extraction of firewood (Navarro et al. 2010). We assess P. pepei as Endangered (A2a, B1a+B2a, C1, D1).

Notes

Polylepis pepei is very similar to P. rodolfovasquezii. It differs by having two pairs of lateral leaflets (versus one pair in P. rodolfovasquezii) and longer inflorescences (1.2–1.6(–3.5) cm) bearing three flowers, whereas P. rodolfovasquezii has shorter inflorescences (0.9–1.1 cm) bearing just one flower. Additionally, P. pepei may be confused with P. subsericans and P. flavipila because they all share short leaflets and inflorescences. Polylepis pepei differs from these by having two pairs of lateral leaflets and sericeous hairs, whereas the other two species have one pair of lateral leaflets and strigose hairs in P. subsericans and pilose hairs in P. flavipila.

Specimens examined

Bolivia. Cochabamba: Chapare, Km 74 Camino antiguo a los yungas del Chapare entrando por Aguirre, 3760 m, 24 April 1999, Mercado 2207 (MO!); 77 km. after Cochabamba on the road to Todos Santos, 4200 m, 04 January 1967, Vuilleumier 465 (MO!, NY, US!). Tiraque, El Ronco, ceja de monte yungena, 17°00'05"S, 065°39'20"W, 3930 m, 11 May 2005, Alcázar-Johansen 403 (BOLV); El Ronco, Ceja de monte yunguena, 17°00'05"S, 065°39'20"W, 3710 m, 11 May 2005, Johansen 403 (MO!). La Paz: Bautista Saavedra, Area Natural de Manejo Integrado Apolobamba, Hilo Hilo, a una hora y media de Pallalani en direccion a Laji Sorapata, sobre el camino, 14°52'40"S, 068°55'34"W, 4300 m, 06 April 2009, Loza 589 (LPB, MA, MO!, USZ); 590 (LPB, MO!, QCA!, USZ). Franz Tamayo, Parque Nacional Madidi, Queara, sector Quecara, Llantai Cunca, 14°39'01"S, 069°05'01"W, 21 April 2008, Fuentes 12687 (BOLV, CTES, HSB, LPB, MA, MO!, QCA!, USZ); Area Natural de Manejo Integrado Apolobamba, Keara, hacia el NW, 14°41'03"S, 069°05'35"W, 4151 m, 17 June 2005, Fuentes 8282 (LPB, MA, MO!, QCA!); Area Natural de Manejo Integrado Apolobamba, Waca Cocha, 4.7 km al SE de Keara, 14°43'47"S, 069°04'17"W, 18 June 2005, Fuentes 8341 (LPB, MO!, QCA!); Area Natural de Manejo Integrado Apolobamba, Hilo Hilo, frente a Pallalani, 14°52'49"S, 068°57'09"W, 4286 m, 05 April 2009, Loza 587 (LPB, MO!, QCA!, USZ); 588 (BOLV, LPB, MO!, QCA!, USZ); Parque Nacional Madidi, Queara nuevo, Chuñuña, queñual al N del pueblo, 14°41'04"S, 069°05'36"W, 4100 m, 09 April 2008, Paco 1 (BOLV, DAV, HSB, LPB, MA, MO!, USZ); Area Natural de Manejo Integrado Apolobamba, Queara nuevo Toilcacocha, 14°41'12"S, 069°05'17"W, 3930 m, 11 April 2008, Paco 80 (LPB, MA, MO!, QCA!, US!); Apolobamba, Puina, cerca de Queñuapata, 14°36'26"S, 069°05'52"W, 4365 m, 10 April 2008, Quisbert 801 (BOLV, LPB, MA, MO!, NY, USZ); 810 (LPB, MA, MO!, USZ); Apolobamba, entre la comunidad de Puina y cerro k’akepununa, 14°36'24"S, 069°05'47"W, 4458 m, 11 April 2008, Quisbert 821 (LPB, MA, MO!, USZ); 825 (BOLV, LPB, MA, MO!, QCA!, USZ); Apolobamba, Palomani, 14°34'58"S, 069°07'38"W, 4286 m, 12 April 2008, Quisbert 844 (BOLV, HSB, LPB, MA, MO!, QCA!, USZ); 848 (BOLV, LPB, MA, MO!, USZ). Inquisivi, 15 Km N Villa Victoria, ca. 15 km SE Quime, 17°06'S, 067°14'W, 4050 m, 05 December 1991, Kessler 3385 (AAU!, GOET!, MO!); 3386 (AAU!, GOET!, MO!). Murillo, entre Pongo y Unduavi, MIna 50, subiendo hacia la Mina SAn Luis, 3960 m, 28 October 1994, Beck 21532 (LPB); Pongo bajanado a los Yungas, del pueblo Pongo subiendo a los restos del bosque de Polylepis pepei, 16°19'32"S, 067°57'26"W, 3950 m, 10 January 2007, Beck 29771 (LPB); Valle del Zongo entrando arriba de Botijalca (Tiquimani) haia el Este, Umapalca media hora y entrando en Valle Latera, 16°12'S, 068°03'W, 4000 m, 31 January 2004, Beck 30014 (LPB); 14.8 km N of the pass at the head of The Zongo Valley, 16°13'S, 068°07'W, 3850–4050 m, 11 April 1987, Brandbyge 584 (AAU!); 854 (MO!); Valle del Río Zongo. 14.8 km al norte de la cumbre, 16°12'S, 068°07'W, 3900–4000 m, 20 February 1987, Solomon 16172 (LPB, MO!); 17.0 km al este de La Cumbre (vieja estación de ferrocarril) por el camino a Unduavi (4.2 km al oeste de Unduavi), 16°19'S, 067°55'W, 3350 m, 11 April 1988, Solomon 18267 (LPB, MO!). Nor Yungas, arriba de Unduavi subiendo aproximadamente 45 min hacia los bosques de Polylepis pepei, 16°18'S, 067°56'W, 4120 m, 13 September 2016, Escobari 78 (LPB). Sud Yungas, debajo de Unduavi, subiendo el valle de Cerromarca, 3450 m, 28 August 1988, Beck 14680 (LPB).

Peru. Puno: San Antonio de Putina, Tocko-Tocko, 14°43'56"S, 69°36'21"W, 4560 m, 10–12 June 1969, Vargas 21596 (CUZ!).

Polylepis rodolfovasquezii L.Valenzuela & I.Villalba, Arnaldoa 22(2): 335, f. 1–2. 2015.

Figs 44, 45

Type

Peru. Junin: Satipo, Pampa Hermosa, rural community of Santa Rosa de Toldopampa, buffer area of the Bosque de Proteccion Pui-Pui, 4221 m, 11°29'33.5"S, 74°56'37.8"W, 21 Apr 2015, Valenzuela & Rojas 28873 (holotype: HOXA!; isotypes: MO!, USM!).

Figure 44. 

Polylepis rodolfovasquezii L.Valenzuela & I.Villaba A flowering branch B flower C flower D habit E leaves (A, B, D Boza et al. 3169). Scale bars: 5 mm (A); 1 cm (B, C, E). Photographs A, B, D G. Vargas C, E T.E. Boza E.

Description

Shrubs or trees 1–8 m tall. Leaves strongly congested at the branch tips, imparipinnate with 1 pair of lateral leaflets, obtrullate in outline, 1.4–1.6 × 1.5–2.0 cm; rachises glabrous, points of leaflet attachment with a tuft of long hairs; stipular sheaths apically with spurs, sparsely sericeous on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 0.9–1.1 × 0.4–0.6 cm; margin entire, apically emarginate with a projection of the mid-vein, basally unequally cordate; upper leaflet surfaces glabrous to sparsely sericeous; lower leaflet surfaces sparsely to densely sericeous with whitish hairs 0.8–1.0 mm long. Inflorescences upright, 0.9–1.1 cm long, bearing 1 flower; floral bracts 4.0–4.8 mm long, narrowly triangular, densely sericeous on the outer surface; rachises glabrous. Flowers 5.7–6.6 mm diam.; sepals 3, ovate, green, densely sericeous outside; stamens 9–10, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 3.6–4.1 mm long. Fruits turbinate often slightly twisted, with variable numbers and placement of short spines, densely sericeous; 4.8–6.0 × 2.6–2.9 mm including spines. Diploid.

Figure 45. 

Polylepis rodolfovasquezii L.Valenzuela & I.Villalba A flowering branch B stipular sheaths C lower and upper leaf surface D fruit E flower (A, B Arce s.n C–E Toivonen 71). Scale bars: 2 cm (A); 1 cm (C); 5 mm (D); 4 mm (E). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis rodolfovasquezii is distributed along the Eastern Cordillera of central Peru from San Martin to Cusco and Puno (Fig. 24). It occurs on wet rocky slopes at 3700–4750 m elevation. It commonly grows with trees of the genera Escallonia, Gynoxys, Hesperomeles and Clethra (Valenzuela and Villalba 2015). Growth of this species is most strongly correlated to growth season temperature (Requena-Rojas et al. 2020a, 2020b). Polylepis rodolfovasquezii remnants harbor several threatened bird species, including Anairetes alpinus (Quispe-Melgar et al. 2018, 2020).

Conservation status

The estimated EOO is 164,207 km2 and AOO is 116 km2. The species is known from 19 locations. Although it is protected within the Pui-Pui Protection Forest in Junin, the species was categorized as VU for Peru (SERFOR 2006, as P. pepei). Burning activities for the expansion of pastures for livestock grazing are causing a reduction of the small remnants, even within the protected area. We assess P. rodolfovasquezii as Vulnerable (A1, B1a+B2a, C1).

Notes

Specimens of this recently described species were long identified as Polylepis pepei, based on their very similar morphology. However, P. rodolfovasquezii differs from P. pepei by having only one pair of lateral leaflets (versus two pairs) and shorter inflorescences (0.9–1.1 cm long) bearing just one flower (versus 1.2–1.6(–3.5) cm long bearing three flowers). When Polylepis rodolfovasquezii was described by Valenzuela and Villalba (2015), they did not realize that their newly described species had been treated as P. pepei since Simpson (1979). Nevertheless, Simpson (1979) already mentioned that “the collection from Peru has only one pair of leaflets, reduced inflorescences and denser covering of trichomes on the under-leaflet surfaces”. Despite these differences from the Bolivian specimens, she recognized just the single taxon P. pepei. This was presumably the result of the low number of specimens known for the two species at that time and the broad species concept adopted by Simpson. Clearly, the two species are closely related allopatric taxa that could conceivably also be treated as subspecies.

Polylepis rodolfovasquezii also resembles P. subsericans and P. flavipila. It differs from these in its shorter inflorescence (0.9–1.1 cm) bearing just one flower, whereas in P. subsericans, the inflorescences are 1.9–5.6 cm long with 3–6 flowers and in P. flaviplia 2.7–4.4 cm long with 3–5 flowers.

Specimens examined

Peru. Cusco: La Convención, bosque de Mandor, 4200 m, 01 October 2004, Palomino 2043 (QCA!); Dist. Santa Teresa, Mountain edges on the lower Eastern portion of the Phachaq valley, Yanama, 13°17'11"S, 072°50'13"W, 4232 m, 28 April 2012, Sylvester 1451 (Z!); Dist. de Ollantaytambo, Mountain edges on the lower Eastern portion of the Phachaq valley, Yanama, 13°17'12”S, 072°50'13"W, 4211 m, 01 May 2012, Sylvester 1501 (Z!); Dist. de Santa Teresa, grazed slopes in the central Pacchaq valley on the East side of the river Yanama, 13°15'40"S, 072°50'17"W, 4268 m, 04 May 2012, Sylvester 1558 (Z!); Dist. Santa Teresa, Mountain edges on the lower Eastern portion of the Phachaq valley, Yanama, 13°17'12"S, 072°50'13"W, 4174 m, 05 May 2012, Sylvester 1564 (Z!); Dist. de Ollantaytambo, topmost forest found on the lower North side of the lower Phachaq valley, Yanama, 13°17'01"S, 072°50'01"W, 4566 m, 15 May 2012, Sylvester 1597 (Z!); 1598 (Z!). Urubamba, Q’esqa, 3960 m, 01 September 2002, Arce s. n. (USM!); Abra Malaga, 13°08'46"S, 072°18'14"W, 4284 m, 01 October 2002, Arce s.n (USM!); Paljay, 13°08'46"S, 072°18'14"W, 4177 m, 01 September 2002, Arce s.n (CUZ!); Chaupiwayco, 13°14'59"S, 072°29'10"W, 4290 m, 01 May 2002, Arce s.n (CUZ!); Piñasniocj, Panticalla pass, 3600 m, 15 July 1915, Cook 1241 (US!); 1837 (US!); Cañon above Peñas ruins towards Nevado Veronica, Peñas Cañon beyond Ollantaytambo on road to Abra Malaga, 4100 m, 26 August 1989, Driesch s.n (GOET!); Cumbre Malaga, 01 October 1984, Rivas s.n (USM!); Dist. de Ollantaytambo, Congunayoc; 3.5 km 175 South of the village Thastayoc, on SE facing slope facing towards Ollantaytambo, 13°10'26"S, 072°16'06"W, 4438 m, 09 March 2012, Sylvester 1392 (Z!); 13°10'24"S, 072°16'14"W, 4415 m, 09 March 2012, Sylvester 1393 (Z!); 13°10'26"S, 072°16'06"W, 4427 m, 10 March 2012, Sylvester 1396 (Z!); 13°10'22"S, 072°16'11"W, 4417 m, 10 March 2012, Sylvester 1397 (Z!); 13°10'25"S, 072°16'14"W, 4414 m, 10 March 2012, Sylvester 1398 (Z!); Machupicchu, Warmiwañuska, 13°14'21"S, 072°29'06"W, 4235 m, 13 September 2006, Toivonen 67; 68; 69; 70; 71; 72; 73; 74; 75; 80 (CUZ!); Ollantaytambo, Abra Malaga, 13°08'40"S, 072°17'51"W, 4340 m, 10 May 2006, Toivonen 82 (CUZ!); Dist. Machupicchu, Microcuenca Pacaymayo; laguna Pacaymayo, 13°13'48"S, 072°29'48"W, 3900 m, 26 June 2001, Tupayachi 5049 (CUZ!); Machupicchu Microcuenca Cusichaca, Sisaypampa Abra Palkay, 13°20'00"S, 072°30'44"W, 4100 m, 28 June 2001, Tupayachi 5155 (CUZ!); 4350 m, 01 July 1915, Bingham 2068 (US!). Junín: Concepcion, Dist. de Comas, localidad de Pomamanta, 11°44'24"S, 075°09'39"W, 4400 m, 23 August 2017, Quispe 76 (CUZ!, USM!, Z!). Satipo, Pampa Hermosa, Toldopampa, 11°29'34"S, 074°56'37"W, 4160 m, 02 August 2016, Boza 3169; 3170; 3171; 3172; 3173; 3174; 3175; 3176; 3177; 3178 (USM!, Z!); Pampa Hermosa. Toldopampa, 13°12'15"S, 075°20'22"W, 4131 m, 02 August 2016, Boza 3179 (USM!, Z!); 3180 (USM!, Z!); Dist. Pampa Hermosa, Comunidad Campesina Santa Rosa de Toldopampa, 11°29'34"S, 074°56'38"W, 4221 m, 21 April 2015, Valenzuela 28873 (HOXA, MO!, USM!). Puno: Limbani, Huancasayani on road to Limbani just east of Abra Aricoma, 14°13'S, 069°42'W, 3750 m, 28 March 1987, Boertmann 130 (AAU!); 512 (AAU!). San Martín: Mariscal Caceres, Dist. de Huicungo, Callejón de Corneadas, 07°57'46"S, 077°23'23"W, 3925 m, 11 June 2001, León 5153 (USM!); Dist. Huicungo, en pirca, debajo del camino de abra Ventanas y Laguna Colorada, 08°00'53"S, 077°23'30"W, 3924 m, 20 June 2010, León 5539 (USM!). San Martín, Dist. de Huicungo, cerca a Laguna Colorada, camino al abra Ventanas, 3900 m, 18 June 2001, León 5260 (USM!).

Polylepis section Reticulatae T. Boza & M.Kessler, sect. nov.

Diagnosis

Trees or shrubs, lower leaflet surfaces tomentose; apices emarginate; fruits with variable numbers and placements of flattened, almost cylindrical or long spines, densely lanose, tomentose or villous.

Type

Polylepis reticulata Hieron.

Notes

The sectional epithet Reticulatae is a plural adjective agreeing in gender with Polylepis. Section Reticulatae, first informally recognized by Simpson (1979) and later recovered as monophyletic in the phylogenetic analysis of Schmidt-Lebuhn et al. (2006a), contains species with relatively few lateral leaflets pairs, rugose or shiny upper leaflet surfaces, emarginate leaflet apices and felt-like covering on the lower leaflet surfaces. All species placed in this section have the lower leaflet surfaces with an evenly distributed dense layer of short, white to yellowish pannose hairs, admixed with short to moderately long tomentose hairs. As in section Sericeae, species in this section have fruits with straight or recurved spines. Polylepis microphylla, P. occidentalis and P. quadrijuga have many lateral leaflet pairs (3–6), but all three have rugose or shiny upper leaflet surfaces and emarginate leaflet apices. The most distinct species of this section is P. hieronymi, which has sparsely tomentose upper leaflet surfaces and almost cylindrical fruits with long spines. This is also the geographically most remote species, being separated by over 1500 km from the other members of the section. Polylepis microphylla also has atypical, turbinate fruits. Polylepis quadrijuga is similar in some ways to P. frontinensis and P. lanuginosa of section Sericeae, but these species do not have the dense layer of short pannose hairs admixed with tomentose hairs on the lower leaflet surfaces. Table 5 provides an overview of the arrangement of the taxa by different authors.

Table 5.

Alignment of the taxa of the Polylepis sect. Reticulatae according to Bitter (1911), Simpson (1979), Segovia et al. (2018) and the present study.

Bitter (1911) Simpson (1979) Segovia et al. (2018) This study
P. brachyphylla P. reticulata P. reticulata P. reticulata
P. nitida
P. reticulata
P. occidentalis
P. hieronymi P. hieronymi P. hieronymi P. hieronymi
P. microphylla P. weberbaueri P. microphylla P. microphylla
P. weberbaueri P. weberbaueri P. simpsoniae
P. weberbaueri
P. quadrijuga P. quadrijuga P. quadrijuga P. quadrijuga

Climatic niches in Polylepis sect. Reticulatae

Many species of this section differ notably in the Mean Annual Temperature (MAT) of their climatic niches, with only P. quadrijuga and P. simpsoniae not being statistically different (Fig. 46). Polylepis hieronymi grows under the highest temperatures (mean of 12.3 °C MAT), followed by P. occidentalis (10.7 °C), whereas P. reticulata (6.4 °C) and P. weberbaueri (5.2 °C) grow under the coldest conditions. These differences of up to 7 °C correspond to elevational differences of well over 1000 m. Regarding Mean Annual Precipitation (MAP), most of the species in this group grow under relatively arid conditions with similar averages of precipitation (807–835 mm MAP). Species growing in even drier areas are P. microphylla (675 mm MAP) and P. weberbaueri (731 mm), whereas those growing in most humid conditions are P. reticulata (1021 mm) and P. quadrijuga (1638 mm). Most species are allopatric, but in Ecuador, P. reticulata and P. simpsoniae co-occur close to each other and have distinct climatic niches, with P. reticulata growing under colder and more humid and P. simpsoniae under warmer and drier conditions.

Figure 46. 

Box plots showing the climatic niches of the species of section Reticulatae in relation to MAT (A) and MAP (B). See Fig. 12 for details on data presentation.

Polylepis hieronymi Pilger, Bot. Jahrb. Syst. 37: 534. 1906.

Figs 47, 48

Polylepis hypoleuca (Weddell) Bitter, Bot. Jahrb. Syst. 45: 607. 1911.

Polylepis racemosa β hypoleuca Weddell, Chlor. Andina 2:238. 1857 [1861]. Basionym. Type. Bolivia. Tarija: between Tarija and San Luis, July-August 1846, Weddell 4607 (lectotype, designated by Simpson 1979, pg. 23: P).

Polylepis racemosa var. albotomentella Kuntze, Revis. Gen. Pl. 3: 77. 1898. Type. Argentina. Córdoba: Sierra de Córdoba, Los Gigantes, Kurtz 6926 (holotype: NY!).

Polylepis australis var. bijuga Bitter (1911: 624) Nom. illeg.

Polylepis hieronymi var. dolicholophaBitter (1911:609). Nom. illeg.

Polylepis hieronymi var. saltensis Bitter, Bot. Jahrb. Syst. 45: 609. 1911. Type. Argentina. Salta: near Pampa Granda, pass “El Alizar”, 2400–2600 m, 1900, Nelson 12584 (holotype: S).

Type

Bolivia. Tarija: Salinas, Cuesta de Polla, Valle del Tambo, June 1873, Lorentz & Hieronymus 938a (holotype: B destroyed; isotypes: G!, GOET!, NY!).

Figure 47. 

Polylepis hieronymi Pilger A flowering branch B upper leaf surface C lower leaf surface D flower and young fruit E stipule sheaths F leaves G flowering branch H bark I flowering branch. Scale bars: 3 cm (A); 1 cm (B, C, F); 5 mm (D, E, G). Photographs by M. Kessler.

Description

Trees 3–8(–25) m tall. Leaves slightly congested at the branch tips, imparipinnate with 3–4 pairs of lateral leaflets, obtrullate in outline, (3.3–)3.6–5.2 × 2.1–3.1 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically truncate with spurs, densely sericeous on the outer surfaces; leaflets narrowly obovate in outline, second pair from the terminal leaflet the largest, one of this pair (1.2–)1.5–2.1 × 0.6–1.0 cm; margin crenate with 5–7 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces sparsely tomentose; lower leaflet surfaces densely tomentose with whitish hairs 0.8–1.1 mm long. Inflorescences pendant, (4.5–)5.6–7.5(–8.1) cm long, bearing 13–25 flowers; floral bracts 3.2–6.3 mm long, narrowly triangular, densely lanate on the outer surface; rachises villous. Flowers 5.4–6.5 mm diam.; sepals 4, ovate, green, densely sericeous outside; stamens 9–19, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.3–3.9 mm long. Fruits almost cylindrical, with variable numbers and placement of long spines, densely lanose; (4.1–)6.0–6.4(–8.3) × 3.5–7.0 mm including spines. Diploid.

Figure 48. 

Polylepis hieronymi Pilger A flowering branch B lower leaf surface C upper leaf surface D fruit E stipular sheaths (A Kessler 3114 B Kessler 3306 C Kessler 3308 D Kessler 3319 E Kessler 3318). Scale bars: 2 cm (A–C); 5 mm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis hieronymi occurs in Boliviano-Tucumanic forests at 1500–3450 m elevation (Fig. 61). It grows in relatively dry areas as a pioneer species that often colonizes landslides and roadsides in mixed forests with Podocarpus parlatorei and Alnus acuminata (Kessler 1995b; Gareca et al. 2010). Trees of P. hieronymi often grow as isolated individuals or small stands mixed in forest dominated by typical high Yungas species. It also occurs on very steep slopes with shallow soils that do not permit persistence of taller trees (Bellis et al. 2014). Thus, the ecology of P. hieronymi is different from that of almost all other Polylepis species, which usually dominate the canopy of the forest they belong to (Renison et al. 2013). Polylepis specialist birds are absent in forests of P. hieronymi, possibly because they do not form large, mature forests (Bellis et al. 2014). Polylepis hieronymi occasionally co-occurs with P. australis in Salta and Jujuy (Argentina) and with P. crista-galli in Chuquisaca (Bolivia), but hybrids have not been found to date.

Conservation status

Based on 28 collecting localities, the estimated EOO is 150,691 km2 and the AOO is 148 km2. It was categorized as VU (B1+2c) in the World List of Threatened Trees (Oldfield et al. 1998). In Bolivia, it occurs in Cordillera de Sama Biological Reserve in Tarija. We assess P. hieronymi as Vulnerable (B1a+B2ac).

Notes

Sterile individuals of P. hieronymi can be confused with sterile plants of P. besseri, also because both species broadly overlap in distribution. Both species have quite similar leaflet shapes and texture, numbers of lateral leaflet pairs and densely tomentose lower leaflet surfaces. If no fruits are available (spiny in P. hieronymi, with broad ridges in P. besseri), they are best distinguished by the sericeous hairs on the stipular sheaths in P. hieronymi and tomentose hairs in P. besseri. Polylepis hieronymi also somewhat resembles P. neglecta in having 3–4 lateral leaflet pairs and relatively long inflorescences with many flowers. However, it has narrowly obovate leaflets with crenate margin and tomentose hairs 0.8–1.1 mm long, styles 2.3–3.9 mm long and spiny fruits, whereas P. neglecta has elliptic leaflets with serrate margins and glabrous to puberulous lower surfaces, shorter styles 1.5–2.2 mm long and winged fruits.

Specimens examined

Argentina. Jujuy: Capital, Tiraxi, Alto Salviar, ladera E, 08 November 1989, Tupayachi s.n (MO!). Salta: Guachipas, Cuesta del La jar, 1600–1700 m, 07 February 1983, Novara 3142 (MO!).

Bolivia. Chuquisaca: Azurduy, Saliendo de Azurduy hacia el río Pilcomayo, 20°12'52"S, 064°26'37"W, 3114 m, 15 October 2007, Cervantes 187 (HSB, MO!); Belisario Boeto, Trayecto Villa Serrano hacia la comunidad de Tampa Mayu y Nuevo Mundo, 19°00'04"S, 064°18'55"W, 2297 m, 12 December 2007, Cervantes 157 B (HSB, MO!); 1 km S Nuevo Mundo on road to Padilla, 19°28'S, 064°10'W, 2200 m, 07 October 1991, Kessler 3306 (GOET!, LPB); 3307 (AAU!, GOET!, MO!); 3308 (AAU!, GOET!, MO!); 3309 (GOET!); 8 km SW Nuevo Mundo on road to Padilla, 19°25'S, 064°11'W, 2500 m, 07 October 1991, Kessler 3317 (GOET!); 3318 (GOET!); 3321 (GOET!); próximo a Lagunillas, 2240 m, 24 January 1988, Murguía 128 (LPB); Hernando Siles, subiendo de la Hacienda Guzman para el Abra, 20°17'16"S, 064°02'56"W, 1993 m, 24 December 2005, Peñaranda 22 (HSB, MO!, QCA!); Oropeza, Municipio de Yotala, Canton Huayllas. Comunidad Pitatorillas, 19°09'06"S, 065°20'48"W, 3374 m, 23 September 2007, Jiménez 376 (HSB, MO!, QCA!). Sud Cinti, Cerro Cobre Khasa, between Culpina and El Palmar, 20°48'S, 064°34'W, 3100 m, 21 September 1991, Fjeldså s.n (GOET!). Tomina, 25 km hacia Montegudo, 19°03'S, 064°16'W, 2400 m, 01 October 1983, Beck 9345 (BOLV, GOET!, LPB, MO!, NY); ca. 20 km SE Padilla on road to Monteagudo, 19°03'S, 064°16'W, 2450 m, 07 October 1991, Kessler 3319 (AAU!, GOET!); Trayecto Lima Bamba – EL Villar, 19°33'01"S, 064°19'55"W, 2553 m, 13 October 2007, Portal 138 (HSB, MO!). Santa Cruz: Mairana, within the Flora de la Region del Parque Nacional Amboro, but above the 700 m contour, 18°06'30"S, 063°57'00"W, 2000–2100 m, Nee 43429 (MO!, NY). Manuel Maria Caballero, Parque Nacional Amboró. San Juan del Potrero; entre Yunguillas y cabeceras del río Zapallar, 17°53'S, 064°25'W, 2300–2400 m, 12–13 May 1992, Vargas 1350 (MO!, NY, USZ). Vallegrande, between “Mataralcito” and “El Palmar” on road from Valle Grande to Tierras Nuevas, 17 km by air ESE of Valle Grande, 18°32'00"S, 065°57'00"W, 2150 m, 29 December 1988, Nee 37403 (NY); camino de Tierras Nuevas a Vallegrande, 18°30'27"S, 063°55'04"W, 2249 m, 31 July 2011, Parada-Gutierrez 3580 (MO!, USZ); camino hacia Khasa Monte, sobre la cima de la serrania, 18°38'09"S, 064°02'01"W, 2550 m, 04 August 2011, Parada-Gutierrez 3671 (MO!, USZ); camino del Cruce hacia Alto Seco, 18°44'45"S, 064°06'53"W, 2717 m, 08 July 2011, Parada-Gutierrez 3746 (MO!, USZ); Senegilla a 17 km de Vallegrande, 18°40'03"S, 064°01'55"W, 2400 m, 20 August 2012, Parada-Gutierrez 4828 (MO!, USZ); a 4 km al norte de Postrervalle sobre el camino a Mairana, 2000 m, 13 November 1999, Saldias 6192 (USZ). Vallegrande, 2363 m, 24 August 2008, Arroyo 4007 (QCA!); Meson at Samaipata, 2200 m, 01 March 1911, Herzog 1786a (GOET!). Tarija: Arce, 43 km hacia Padcaya, Huancanqui, 2500–2600 m, 20 November 1986, Beck 14080 (GOET!); cerca de Camacho, 2600 m, 17 December 1987, Beck 16067 (GOET!); bajando del Abra del Cerro Cabildo hacia el S via estancia Cabildo, 2350 m, 29 January 1988, Beck 16240 (GOET!); ca. 5 km W Padcaya, 21°54'S, 064°46'W, 2200 m, 18 September 1991, Kessler 3114 (AAU!, GOET!); 3646 (GOET!); detras de Padcaya, 2450 m, 23 January 1988, Liberman 1637 (GOET!); Municipio Padcaya, Cantón Emborozú, Reserva Natural Alarachi, recorrido a cima más alta de la Zona Alarachi, próximo al Cerro Yauparuna, 22°10'44"S, 064°36'33"W, 2260–2380 m, 16 September 2004, Serrano 4828 (MO!); 39.9 km S of jct. of road to Entre Rios, on road to Padcaya, 21°54'S, 064°41'W, 2100–2200 m, 29 April 1983, Solomon 10218 (LPB, MO!, NY). O’Connor, ca. 5 Km W Padcaya, 21°54'S, 064°46'W, 2200 m, 18 September 1991, Kessler 3113 (AAU!, GOET!, MO!); 3115 (GOET!, MO!); ca. 70 km on road from Tarija to Entre Rios, 21°26'S, 064°19'W, 2200 m, 20 September 1991, Kessler 3123; 3124 (AAU!, GOET!); 3125 (GOET!, MO!); 3660 (AAU!, GOET!, MO!); 21.1 km on road to entre Rios, 21°27'S, 064°20'W, 1900 m, 01 October 1983, Solomon 10918 (LPB, MO!). Valle del Tambo bei Tarija, 10 June 1973, Hieronymus 938 (GOET!); Cult. at Jardin Botanico La Paz 2000 from seeds, s.d., Kessler 12625 (GOET!). s.d., Cárdenas 3906 (US!); 3907 (US!); Salinas, Cuestas de Polla, in valle Tambo, June 1873, Hieronymus 938a (B, F!); s.d., Hieronymus 938a (B, MO!).

Polylepis microphylla (Wedd.) Bitter, Bot. Jahrb. Syst. 45: 611. 1911.

Figs 49, 50

Polylepis microphylla var. polyarthotricha Bitter, Bot. Jahrb. Syst. 45: 612. 1911. Type. Goudot 1 (holotype: W).

Basionym

Polylepis lanuginosa var. microphylla Weddell, Chlor. Andina 2:238.1861.

Type

Ecuador. Chimborazo: Humboldt & Bonpland 3141 (holotype: P!; isotypes: F!, GOET! US!).

Figure 49. 

Polylepis microphylla (Wedd.) Bitter A leaves B stipule sheaths C flowering branch D habit E lower leaf surface F flowering branch G habit. Scale bars: 1 cm (A, E); 5 mm (C, F); 1 mm (B). Photographs A, C T.E. Boza E. D, F E.G. Urquiaga F. B, E M. Kessler G E. Bastidas.

Description

Shrubs and trees 1.5–8 m tall. Leaves strongly congested at the branch tips, imparipinnate with 3–6 pairs of lateral leaflets, obtrullate in outline, (1.3–)2.0–3.5 × (0.6–)1.2–1.5 cm; rachises densely tomentose often intermixed with twisted dark red hairs; stipular sheaths apically acute with spurs, densely tomentose on the outer surfaces; leaflets broadly elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 0.3–0.7 × 0.2–0.5 cm; margin entire, apically deeply emarginate, basally unequally cordate; upper leaflet surfaces glabrous or sparsely tomentose mainly in the mid-vein depression; lower leaflet surfaces densely tomentose with whitish hairs 0.8–1.0 mm long. Inflorescences branched at the base or simple, pendant, 3.8–5.3 cm long, bearing 1–3 flowers; floral bracts 2.2–2.5 mm long, narrowly triangular, densely tomentose on the outer surface; rachises tomentose. Flowers 4.0–6.4 mm diam.; sepals 4, ovate, green, glabrous outside; stamens 9–11, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.6–3.5 mm long. Fruits turbinate, with variable numbers of long spines, densely tomentose; 2.7–4.3 × 1.3–2.1 mm including spines. Diploid and tetraploid.

Figure 50. 

Polylepis microphylla (Wedd.) Bitter A branch B leaves C stipular sheaths D upper and lower leaves surface (A Toivonen 98 B Boza 3001 C Toivonen 19 D Irazabal 205). Scale bars: 2 cm (A–C); 5 mm (D). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis microphylla occurs in small, isolated populations in the central Ecuadorian Andes on the slopes of Volcán Chimborazo, in north-western Peru in the high Andes of Cajamarca, the Cordillera Blanca and the adjacent Cordillera Huayhuash at the boundaries of Ancash and Lima and in Arequipa and Cusco (Fig. 61). It grows mainly in arid zones at 3150–4550 m elevation where it usually forms small groves, but many populations in areas strongly affected by human activities contain mostly small shrubs. However, in the Cordillera Huayhuash, extensive stands with trees about 3–5 m tall can be found. The populations in Cusco are close to Incan ruins and might represent historical transplantations (Kessler and Schmidt-Lebuhn 2006).

Conservation status

The EOO is estimated as 407,902 km2 and AOO as 100 km2. The species is known from 18 locations. The two forests in Ecuador form a single genetic population (Bastidas-León et al. 2021). It is protected within Sangay National Park in Ecuador and Huascarán National Park and Cordillera Huayhuash Reserved Zone (within Huayllapa Private Conservation Area) in Peru. The species was categorized as VU (B1+2c) in the World List of Threatened Trees (Oldfield et al. 1998). Lately, based on its restricted distribution in Chimborazo, P. microphylla was categorized as CR (B2ab(iii)) in Ecuador (León-Yánez et al. 2011; Tejedor et al. 2014, 2015). In Peru, where it is more widespread, P. microphylla was categorized as EN (SERFOR 2006). At many of its locations, the species grows in habitats that are strongly affected by human activities including grazing and burning. We assess P. microphylla as Endangered (B1a+B2ab).

Notes

Polylepis microphylla was included in P. weberbaueri by Simpson (1979), based on material from Cañar (Ecuador) that contains lower mature leaves like those of P. weberbaueri (here assigned to P. simpsoniae) and upper young leaves similar to those of the specimens placed under P. microphylla by Bitter (1911). Later, P. microphylla was considered as a distinct species by Romoleroux (1996), based on newly collected material from Chimborazo that does not have such differences between mature and younger leaves. Polylepis microphylla differs from P. simpsoniae by smaller leaflet size (0.3–0.7 × 0.2–0.5 cm versus 0.9–1.6 × 0.4–1.1 cm), longer leaflet hairs (0.8–1.0 mm versus 0.5–0.7 mm) and inflorescences with lower number of flowers (1–3 versus 3–5).

Specimens examined

Ecuador. Chimborazo: Alausí, camino Totoras-Charicando, 02°11'30"S, 078°42'18"W, 3500 m, 08 July 2004, Caranqui 1205B (CHEP); Shumit, Pucara Achupallas, 3986 m, 04 September 2009, Cárate 1200 (QCA!); carretera Alausí-Achupallas-Osogoche, 3300–3400 m, 10 August 1987, Romoleroux 372 (AAU!, NY, QCA!); Vía Achupallas-Osogoche, km 14.5, localidad Zula, 3600 m, 24 March 2001, Romoleroux 3995 (QCA!); Alausí-Achupallas, Páramo Parada 1, 3576 m, 17 March 2007, Romoleroux 4414 (QCA!); Alausí-Achullapas, 3655 m, 17 March 2007, Romoleroux 4435 (QCA!); Vía Totoras Achupallas, Lagunas de Osogoche, 3626 m, 08 November 2008, Romoleroux 5325 (QCA!); Vía desvío Osogoche-Achupallas, 3589 m, 28 December 2011, Romoleroux 5704 (QCA!); Vía Achupallas-lagunas de Osogoche, km 11.5, 3000 m, 26 April 1988, Romoleroux 576 (AAU!, MO!, QCA!); Vía Achupallas-lagunas de Osogoche km 11.5, 3650 m, 26 April 1988, Romoleroux 577 (AAU!, NY, QCA!); 3650 m, s.d., Romoleroux 578 (AAU!, NY, QCA!); Vía Achuapallas-Lagunas de Osogoche, km. 15, 3650 m, 26 April 1988, Romoleroux 579 (AAU!, MO!, NY, QCA!); 3650 m, Romoleroux 580 (AAU!, NY, QCA!); Vía Achupallas-Lagunas de Osogoche, km 15, 3650 m, 26 April 1988, Romoleroux 581 (AAU!, NY, QCA!); Vía Osogoche-Achupallas, 3610 m, 30 September 2016, Romoleroux 6126 (QCA!); Vía Osogoche-Achupallas, 3610 m, 30 September 2016, Romoleroux 6127 (QCA!); Vía Osogoche-Achupallas, 02°15'53"S, 078°42'09"W, 3610 m, 09 March 2017, Romoleroux 6148 (QCA!); Alausí-Achupallas, 3655 m, 17 March 2007, Romoleroux GPI4435 (QCA!), Quitesian Andes, s.d., Cothouy s.n (NY); 1857–1864, Spruce s.n (MO!).

Peru. Ancash: Huaylas, Caraz, Laguna Parón, flanco norte, 4170 m, 27 April 2013, Baldeón 7816 (USM!); Caraz, Laguna Paron, Irazábal 199 (CUZ!); Yungay, Parque Nacional de Huascaran, laguna Paron, 08°59'55"S, 077°41'26"W, 4200 m, 11 February 1997, Tupayachi 3271 (CUZ!). Cajamarca: San Miguel, San Miguel de Pallaques, road Agua blanca to Oyotum, Ponga la Mesa, 3500–3600 m, 14 October 2000, Weigend 2000/748 (F!, USM!). Cusco: Acomayo, Queuñayocpampa, 14°04'01"S, 071°35'08"W, 3940 m, 01 April 2003, Arce s.n (USM!); Rondocan, localidad Parara, 13°47'10"S, 071°45'08"W, 4085 m, Pfuro AS-133 (Z!). Calca, Pisac, 13°25'S, 071°51'W, 3400 m, 10 February 2003, Lægaard 22250 (AAU!). Cusco, Huacoto, 13°30'54"S, 071°51'19"W, 3960 m, 01 May 2003, Arce s.n (USM!); Chacan, 13°29'04"S, 071°59'26"W, 3805 m, 17 September 2014, Boza 3001; 3002 (USM!, Z!); Cuzco, Chacan camino al grupo arqueológico, borde de la microcuenca Chacan, 3600 m, 03 October 2000, Galiano 3999 (QCA!); Huacoto, 3991 m, Irazábal 204 (CUZ!); Chacan S of Cusco, 13°29'S, 072°00'W, 3900 m, 10 February 2003, Lægaard 22350 (AAU!, US!); San Jerónimo, localidad de Huacoto, 13°31'06"S, 071°51'32"W, 3940 m, 25 May 2006, Toivonen 19 (CUZ!); 20 (CUZ!); 21 (CUZ!); Chacan, 14 June 2006, Toivonen 98 (CUZ!); Chacan, 14 June 2006, Toivonen 99 (CUZ!); Ruinas de Pisac, 3200 m, 01 May 2002, Toivonen s.n (CUZ!); Chacan, 3600 m, 28 April 1993, Tupayachi 2280 (CUZ!). Quispicanchis, Dist. Huaro, Urpay, 13°41'01"S, 071°38'22"W, 3200 m, 01 November 2002, Galiano 4512 (AMAZ, CUZ!, HUT, MO!, MOL, USM!). Urubamba, Cusco. Prov. Urubamba, Yucay, Hatum Wayko, 3500 m, 09 September 2001, Herrera 4175 (QCA!); Yucay, 3833 m, Irazábal 207 (CUZ!); Yucay, cerro Turukuntur, 3750 m, 13 January 1991, Tupayachi 1460 (CUZ!). Lima: Cajatambo, Huayllapa. Dist. de Copa, cerro empinado a 115 km del pueblo, 3360 m, 13 May 2001, Callupe 1 (USM!).

Polylepis occidentalis T.Boza & M.Kessler, sp. nov.

Figs 51, 52

Diagnosis

Resembles the Ecuadorian species, P. reticulata Hieron. by having 3–5 lateral leaflet pairs and similar type and density of hairs, but differs by its shorter hairs (0.3–0.6 mm vs. 0.6–1.5 mm), shorter inflorescences (2.4–6.7 cm vs. 2.3–13.8 cm) and shorter styles (1.5–2.0 mm vs. 2.6–3.9 mm).

Figure 51. 

Polylepis occidentalis T.Boza & M.Kessler A leaves B leaf C upper leaf surface D lower leaf surface E fruit. Scale bars: 2 cm (A); 1 cm (B–D); 3 mm (E). Photographs A, B M. Richter C–E T.E. Boza E.

Type

Peru: Piura: Huancabamba, Talanco, 2900 m, 5 Nov 1976, A. Sagastegui A.8635 (holotype: MO!; isotype: UMO!).

Figure 52. 

Polylepis occidentalis T.Boza & M. Kessler A flowering branch B fruit C stipular sheaths D lower leaf surface E upper leaf surface (A Dillon 4145 B, D, E Diaz 4012 C Beltran 6933). Scale bars: 4 cm (A); 4 mm (B); 2 cm (D, E). Photographs by T. E. Boza E.

Description

Trees 3–15 m tall. Leaves slightly congested at the branch tips, imparipinnate with 3–5 pairs of lateral leaflets, obtrullate in outline, 3.1–4.7 × 1.8–2.9 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.1–1.9 × 0.5–0.8 cm; margin entire or slightly crenate at the apex with 3–6 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.3–0.6 mm long. Inflorescences pendant, 2.4–6.7 cm long, bearing 4–12 flowers; floral bracts 6.8–7.6 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers 6.8–7.6 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 9–15, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 1.5–2.0 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 3.8–4.1 × 5.8–7.1 mm including spines. Diploid.

Distribution, habitat and ecology

Polylepis occidentalis is distributed in the high mountains of western Peru from Huancabamba (Piura) to Pataz (La Libertad) (Fig. 61). The species occurs in relatively dry forest at 2200–3990 m elevation.

Etymology

The species epithet “occidentalis” (Latin: western) refers to the distribution range occupying the western mountains in Peru.

Conservation status

The EOO for Polylepis occidentalis is estimated as 12,906 km2 and the AOO at 52 km2. It is known from 11 locations. It has been found in monospecific forests at the southern margins of the Huancabamba Andean Depression, which forms an important dispersal corridor for Andean tree species (Richter et al. 2009; Peters et al. 2014). However, collections from Cajamarca, La Libertad and Lambayeque are mostly old and the collection areas have undergone heavy deforestation. Based on the reduction of its restricted distribution and its habitat degradation, we assess P. occidentalis as Endangered (A1, B1a+B2a, C1).

Notes

The populations of Polylepis section Reticulatae from western Peru have been previously identified either as P. reticulata (Lassermann 2009) or P. weberbaueri (Simpson 1979; Lassermann 2009; Mendoza and Cano 2012; Peters et al. 2014) (Fig. 34). Certainly, P. occidentalis resembles P. reticulata in having 3–5 lateral leaflet pairs and same type and density of hairs. However, it has shorter lower leaflet surface hairs (0.3–0.6 mm long), shorter inflorescences (2.4–6.7 cm long) and shorter styles (1.5–2.0 mm long), whereas P. reticulata has lower surface hairs 0.6–1.5 mm long, inflorescences (2.1–)4.3–13.8 cm long and styles 2.6–3.9 mm long. Additionally, P. occidentalis occurs in western Peru, whereas P. reticulata is distributed in Ecuador. Polylepis occidentalis is morphologically also similar to P. weberbaueri, with which it shares similar leaflet size and lower leaflet surface hair type and density. The most obvious differences between P. occidentalis and P. weberbaueri are leaflet pair number, inflorescence length, style length and number of stamens, with P. occidentalis having 3–5 leaflet pairs, inflorescences 2.4–6.7 cm long, styles 1.5–2.0 mm long and 9–15 stamens, whereas P. weberbaueri has 2–3 leaflet pairs, inflorescences 8.2–9.7 cm long, styles 2.7–3.2 mm long and 19–21 stamens.

Simpson (1979) considered P. reticulata and P. weberbaueri to occur in both Ecuador and Peru, with the populations of each species separated by the low elevation Huancabamba depression. Interestingly, however, defined in this way in Ecuador, P. “reticulata” occurs at higher elevations than P. “weberbaueri”, whereas in Peru, the reverse is the case. In addition to the morphological traits outlined above, we consider this intriguing distributional pattern to support treatment as four species, with the original P. reticulata restricted to Ecuador and P. weberbaueri to Peru and the respective other populations here described as P. occidentalis (Peruvian P. “reticulata”) and P. simpsoniae (Ecuadorean P. “weberbaueri”).

Specimens examined

Peru. Cajamarca: Cajamarca, Dist. La Encañada, San Pedro de Lipiac, 07°03'38"S, 078°20'00"W, 3738 m, 07 September 2010, Beltrán 6933 (USM!). Chota, Llama; caserío Callampampa; afluente de Huarimarca, 2800–3000 m, 19 January 1990, Díaz 4012 (MO!, USM!); Laguna Yahuarcocha (arriba de Incahuasi), 07°34'45"S, 077°58'29"W, 3600 m, 14 September 1985, Sagástegui 12896 (GOET!, IBE, MO!); Tucupampa (Llama-Huambos), 2500 m, 17 March 1997, Sagástegui 15950 (F!, MO!); Miracosta, entre Miracosta y Pampa del Lirio, 06°23'S, 079°15'W, 3250 m, 11 November 2000, Sánchez 10285 (MO!); Huambos, 2000 m, 11 September 1956, Soukup 4457 (F!). Cutervo, carretera entre Llama y Huambos, Tunaspampa, 06°31'52"S, 079°05'26"W, 2600–2900 m, 21 April 1988, Díaz 2879 (F!, MO!). Huambos, 65 km E of bridge over Río Maichil, 25 km W of Huambos, 06°25'S, 079°00'W, 2700 m, 09 February 1988, Gentry 61439 (MO!, USM!). Llama, El Pargo, 4.2 km E of Llama, ca. 1.4 km SE of Tunas Pampas, 06°30'S, 079°31'W, 3000 m, 08 September 1991, Gentry 74575 (MO!, USM!). La Libertad: Pataz, Chirimachay, 07°00'S, 077°00'W, 3450 m, 24 February 1986, Young 2966 (MO!). Lambayeque: Ferrenafe, Ca. 7 km NW of Incahuasi; near Cerro Punamachay on trail to Laguna Hualtaco, 3300–3550 m, 16 November 1984, Dillon 4145 (MO!, USM!). Piura: Huancabamba, 38 km above Canchaque, just below summit, 05°18'08"S, 079°29'54"W, 3120 m, 13 September 1964, Hutchison 6578 (A!, MO!, USM!); Talaneo (Jalca - Cixse), 2900 m, 05 September 1976, Sagástegui 8635 (MO!, UMO). Unknown minor area, La Cruz, 04 June 1961, Acleto 364 (GOET!, USM!); Paso de la Cruz Blanca, 3307–3154 m, 13 November 2007, Lasermann I5-8 (USM!); Paso de la Cruz Blanca, 3307 m, 13 November 2007, Lasermann V/3 (USM!).

Polylepis quadrijuga Bitter, Bot. Jahrb. Syst. 45: 613, pl. 6. 1911.

Figs 53, 54

Polylepis boyacensis Cuatrecasas, Revista Acad. Colomb. Ci. Exact. 4: 343, f. 13–14. 1941. Type. Colombia. Boyacá: Cordillera Oriental, Páramo de Santa Rosita between Belen and Susacon, 3300–3400 m, 3 August 1940, Cuatrecasas 10374 (holotype: P!; isotypes: COL!, US!).

Polylepis cocuyensis Killip & Cuatrecasas, Revista Acad. Colomb. Ci. Exact. 5(17): 33. F. 19.1942. Type. Colombia. Boyacá: Nevado del Cocuy in the Quebrada of San Paulino, El Morrón, 3800 m, 11 September 1938, Cuatrecasas 1405 (holotype: US!; isotypes: P!, U!).

Type

Colombia. Cundinamarca: Cordillera Oriental, Páramos de Bogota, Muzo, May 1844, Goudot s.n (holotype: P!).

Figure 53. 

Polylepis quadrijuga Bitter A flowering branches B habit C habit. Scale bars: 3 cm (A). Photographs by D. Cabrera.

Description

Trees 2–10 m tall. Leaves slightly congested at the branch tips, imparipinnate with 3–4 pairs of lateral leaflets, obtrullate in outline, (4.2–)4.4–5.3(–6.5) × 2.4–3.2 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.5–2.0 × 0.7–1.1 cm; margin entire or slightly crenate with 4–6 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.7–0.9 mm long. Inflorescences pendant, (6.0–)7.3–10.5(–12.3) cm long, bearing 11–19 flowers; floral bracts 4.3–4.7 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers 6.8–9.5 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 9–19, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 3.7–4.6 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 4.6–6.5(–7.2) × 5.1–7.2 mm including spines. Diploid.

Figure 54. 

Polylepis quadrijuga Bitter A flowering branch B stipular sheaths C inflorescence D upper leaf surface E lower leaf surface (A Montenegro 2717 B Huerta 6565 C Cuatrecasas 27741 D, E Stancik 2463). Scale bars: 3 cm (A); 4 cm (C); 2 cm (D, E). Photographs by J. M. Vélez.

Distribution, habitat, and ecology

Polylepis quadrijuga is found in north-eastern Colombia from Páramo de la Rusia (Santander) across Páramo Guina, Páramo Belen, Páramo Guantiva and Sierra Nevada Cocuy (Boyacá) to Maciso de Sumapáz and Chingaza National Natural Park (Cundinamarca) (Fig. 61). It grows in humid Páramos at 2200–4250 m elevation. Polylepis quadrijuga represents 33.7% (1032.2 ha) of the total area of Polylepis forest identified for Colombia (Fadiño and Caro 2009). It is often associated with Diplostephium tenuifolium (Asteraceae) and Escallonia myrtilloides (Escalloniaceae) (Rangel-Ch and Arellano 2010).

Conservation status

The estimated EOO for Polylepis quadrijuga is 16,286 km2 and the AOO is 84 km2. It is known from 16 locations. Polylepis quadrijuga is protected within Chingaza and Sumapaz National Natural Parks and Cocuy National Park. Although the species occurs within these protected areas, it is also found in heavily fragmented forest regions. Perhaps the most worrying area is the corridor Rusia-Guantiva Páramos because of the absence of protected areas that would help to mitigate the current pressures (Rangel-Ch and Arellano 2007). The rising of the potato crop line is a strong threat to the permanence of these forests (Rangel-Ch and Arellano 2010), as is the reduction of the potential range due to climate change (Caballero-Villalobos et al. 2021). We assess P. quadrijuga as Vulnerable (A2a, B1a+B2a, D2a).

Notes

Polylepis quadrijuga resembles P. frontinensis. It differs from it by its elliptic leaflets with tomentose hairs 0.7–0.9 mm long, whereas P. frontinensis has obovate leaflets with villous hairs 1.4–1.8 mm long. Further, P. quadrijuga is morphologically similar to P. occidentalis, with which it shares elliptic leaflets, with deeply emarginate apices, entire to slightly crenate margins and densely tomentose lower leaflet surfaces. However, P. quadrijuga has broader leaflets 0.7–1.1 cm, longer lower leaflet surface hairs 0.7–0.9 mm, longer inflorescences 6.0–12.3 cm, bearing 11–19 flowers and longer styles 3.7–4.6 mm, whereas P. occidentalis has leaflets 0.5–0.8 cm width, lower leaflet hairs 0.3–0.6 mm long, inflorescences 2.4–6.7 cm long with 4–12 flowers and styles 1.5–2.0 mm long.

Specimens examined

Colombia. Boyacá: Duitama, Corregimiento El Carmen, vía a Virolin, Páramo de La Rusia, 3400–3500 m, 19 November 1994, Betancur 5610 (COL!); Páramo de Rusia. Km 3 from the summit of the road Duitama-Abendaños, 3500 m, 12 February 1999, Stancík 2384 (COL!). El Cocuy, Cordillera Oriental, Sierra Nevada del Cocuy, Quebrada de San Paulino próximo Alto Ritacuva, 3500 m, 07 April 1959, Barclay 7303 (COL!, MO!); Cocuy National Park, Concavito Valley, 06°25'39"N, 072°19'15"W, 4000 m, 07 February 2017, Olivares 570 (Z!). Guicán, Guican. Alto de la Cueva limite Cocuy-Guican, Finca Eudoro Carreño y Margarita Carreño, estación del Himat, 06°24'33"N, 072°22'40"W, 3930 m, 14 October 1996, Cruz 164 (COL!). Susacon, 20 km passing Sussacon in direction to soata, 3150 m, 23 February 1999, Stancík 2463 (COL!). Cordillera Oriwntal; Páramo de Guina-Santa Rosita, 3300–3400 m, 03 August 1940, Cuatrecasas 10374 (US!); NNW de Duitama, Páramo de La Rusia, Avenida de Peñas Negras (Buenos Aires), 3550 m, 11 September 1989, Cuatrecasas 27741 (COL!); Hoya del Río Cusiana, Vadohondo, 2880 m, 31 March 1973, Cuatrecasas 28708 (COL!); Mpio. de Guican, vereda La Guaca, El Junco, 3716 m, 23 July 1981, López s.n (COL!); arriba de la confluencia con el río Upía, Río Olarte, 3015 m, 27 February 1955, Molano s.n (COL!); Páramo de Colorado, 3200 m, 11 May 1960, Montenegro 2717A (COL!). Cundinamarca: Pasca, Vereda Cajita, borde de Laguna Cajitas en el Páramo de Chisacá, 3700 m, 04 October 1983, Sarmiento 2000 (COL!). Santafé de Bogotá, Macizo de Sumapáz; Cuchilla La Rabona, 04°04'40"N, 074°13'00"W, 3900–3950 m, 17 July 1981, Díaz 2902B (COL!, MO!); Bogotá, D.C. Páramo de Sumapaz. ladera de la laguna Tunjos (Chisacá), 04°16'36"N, 074°12'17"W, 3725 m, 19 February 1997, Franco 5632 (COL!, MO!). Subachoque, Vereda Tobal, 2800 m, 09 November 2003, Hernández 1407 (COL!); carretera Cogua-San Cayetano, cebeceras Río Guandoque, 3 km al SW de la Laguna Verde, 3400 m, 01 June 1972, Cleef 4213 (COL!); Macizo de Bogotá, eastern slopes of Páramo de Chisaca. Quebrada de Santa Rosa, subPáramo, 3300–3350 m, 16 September 1961, Cuatrecasas 25999 (COL!); Dist. Especial de Bogotá; cordillera Oriental; lagunas de Chisacá; 40 km al N de Sumapaz, 3300–4000 m, 10 September 1959, García 17192 (AAU!); Fomeque, Páramo de Chingaza, a orillas de La Laguna, 3200 m, 03 November 1966, Huertas 6565 (COL!); Mpio. Bogota, Páramo de Sumapaz, entre la Laguna de Chisaca y Santa Rosa, 01 May 1989, Mahecha 10121 (COL!); Usme, al sur de Bogotá, 01 January 1944, Ranghel s.n (COL!); Macizo de Sumapaz, cerca a Santa Rosa, 3600–3700 m, 30 September 1963, Uribe 4491 (COL!). Santander: Encino, Vereda Rionegro, Microcuenca de la quebrada Chontales, 05°59'N, 073°04'W, 3400–3500 m, 15 December 1999, Galindo 300 (COL!).

Polylepis reticulata Hieron., Bot. Jahrb. Syst. 21: 312. 1896.

Figs 55, 56

Polylepis brachyphylla Bitter, Bot. Jahrb. Syst. 45: 616. 1911. Type. Ecuador. Bolivar: Volcán Chimborazo, slopes towards Guaranda, 4 November 1856, Remy s.n (holotype: P!; isotypes: GOET!, P!).

Polylepis nitida Bitter, Bot. Jahrb. Syst. 45: 615. 1911. Type. Ecuador. Tungurahua: Minza at Volcan Tungurahua, 3600 m, Stübel 287 (holotype: B destroyed; photos at F!, GH, MO!, NY, US!).

Type

Ecuador. Pichincha: near Las Calderas de Pasachoa and Rumiñaqui, Stübel 20a. (holotype: B destroyed; photos at F!, GH, NY, US).

Figure 55. 

Polylepis reticulata Hieron A flowering branch B leaves C stipule sheaths D upper leaflet surfaces E lower leaflet surfaces F juvenile leaves G bark H fruit I dried fruit. Scale bars: 5 mm (A, B); 1 cm (C–F); 3 mm (H); 2 mm (I). Photographs by T. E. Boza E.

Description

Trees 2–15 m tall. Leaves slightly congested at the branch tips, imparipinnate with (1–)2–3(–4) pairs of lateral leaflets, obtrullate in outline, (1.3–)2.6–4.2(–7.0) × (1.5–)2.2–3.6 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic to obovate in outline, second pair from the terminal leaflet the largest, one of this pair (0.9–)1.2–2.2 × 0.4–1.1 cm; margin entire or slightly crenate at the apex with 3–5 teeth, apically deeply emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.6–1.5 mm long. Inflorescences pendant, (2.3–)4.3–13.8) cm long, bearing 5–9 flowers; floral bracts 3.1–8.0 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers 6.2–12.2 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 7–9, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.6–3.9 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 3.4–6.0 × 2.9–8.3 mm including spines. Diploid and hexaploid.

Figure 56. 

Polylepis reticulata Hieron A flowering branch B leaves C lower leaf surface D upper leaf surface E fruit (A Laegaard 102646 B Laegaard 20601 C–E Laegaard 52886). Scale bars: 3 cm (A, C, D); 2 cm (B); 5 mm (E). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis reticulata is found in Carchi, Imbabura, Pichincha, Tungurahua, Bolivar, Chimborazo, Azuay and Loja (Ecuador) (Fig. 61). It grows under relatively dry conditions (except at Llanganates and Pasochoa that are more humid) in Andean forest at 2750–4600 m elevation. It often co-occurs with P. simpsoniae in Azuay. In Sacha Huayco Forest (Chimborazo) at 4000–4500 m elevation, the canopy layer is comprised almost completely by P. reticulata, with Gynoxys sp. dominating the subcanopy (Osha 2000). At 4300 m elevation in Chimborazo Wildlife Production Reserve, trees of P. reticulata are, on average, 2.8 m tall (maximum 8.2 m) with diameters of 8.6 cm (maximum 16.9 cm) (Castillo et al. 2017). In Cuenca (Ecuador), the minimum temperature threshold of vegetative growth activity was found to be close to 6 °C (Saravia et al. 2016). In the same forest, mean annual litterfall is 3.77 Mg ha-1, representing 51% of the canopy leaf biomass, indicating a leaf life span of 1.98 years and a mean decomposition rate of 0.38 year-1 (Pinos et al. 2017). Diameter growth rates measured over seven years average 1.2 mm/year and the average carbon sequestration rate is 2.6+/-0.3 Mg C. ha-1 year-1, which is high for this generally slow-growing genus (Montalvo et al. 2018). Tree rings of P. reticulata are characterized by semi-ring porosity and minor changes in fiber wall thickness between latewood and earlywood. Tree ring width is more related to temperature than precipitation (Alvites et al. 2019). Based on an AFLP study, clonal propagation affects the fine-scale genetic structure within a spatial distance of 3 m (Peng et al. 2015). In a forest of P. reticulata, the soil had low microbiological quality with low biological activity, even though there were some beneficial nematodes representing a great advantage for the elimination of insect pests that could affect Polylepis (Castillo et al. 2017). Hybrids with P. pauta have been found in Pichincha.

Conservation status

The EOO for Polylepis reticulata is estimated as 33,103 km2, the AOO is assessed at 324 km2 and it is known from 40 locations. Most of the populations occur in protected areas. There are populations in the Cajas (Azuay), Llanganates (Tungurahua) and Yacuri (Loja) National Parks, Chimborazo Wildlife Production Reserve, Illinizas Ecological Reserve (Pichincha) and in part of Pasochoa Ecological Reserve. However, P. reticulata was categorized as Vulnerable VU (A4c) (León-Yánez et al. 2011). Although the species occurs within national parks, its populations are heavily fragmented. We assess P. reticulata as Vulnerable (B1a+B2a, C1).

Notes

Polylepis reticulata shows some degree of morphological differentiation between juvenile and adult leaves, with the young leaves having more lateral leaflet pairs (4 versus 1–3), slightly crenate margins (versus entire) and sparsely tomentose in the upper leaflet surfaces (versus glabrous). This differentiation was the basis for the recognition of three species by Bitter (1911) in what is now recognized to be a single species.

Polylepis reticulata is morphologically closest P. occidentalis, with which it shares similar leaflet size, margin types and number of lateral leaflets pairs. It differs by its longer lower leaflet surface hairs (0.6–1.5 mm), longer inflorescences ((2.3–)4.3–13.8 cm) and longer styles (2.6–3.9 mm), compared to the shorter lower leaflet surface hairs (0.3–0.6 mm), shorter inflorescences (2.4–6.7 cm) and shorter styles (1.5–2.0 mm) of P. occidentalis. Polylepis reticulata is also morphologically close to P. simpsoniae, with which it shares similar leaflet surface hair type and density. The most obvious differences between P. reticulata and this species are leaflet length (0.9–2.2 cm versus 0.9–1.6 cm), length of hairs on the lower leaflet surfaces (0.6–1.5 mm versus 0.5–0.7 mm) and longer inflorescences ((2.3–)4.3–13.8 cm versus (2.5–)3.7–3.9(–5.5) cm).

Specimens examined

Ecuador. Azuay: Chaucha, Páramo de Soldados, 02°53'S, 079°18'W, 3700–4000 m, 28–29 August 1985, Lægaard 55114C (AAU!). Cuenca, Páramo de Cajas, 3650–3890 m, s.d., Boeke 631 (MO!, QCA!); Parque Nacional El Cajas, 02°50'S, 079°12'W, 3500 m, 19 September 1983, Brandbyge 42269 (MO!); Along the río Matadero, west Cuenca, 03 March 1945, Camp E-2000 (MO!); along the río Matadero, west Cuenca, 3500 m, 03 March 1945, Camp E-2000 (MO!, NY, US!); Area Nacional de Recreación Cajas, Laguna Toreadora and Virgen Machay, 02°46'S, 079°13'W, 4000–4400 m, 18 December 1995, Clark 1794 (MO!, QCNE); Parque Nacional El Cajas, Laguna Toreador, 02°53'S, 079°08'W, 3500 m, 19 April 1998, Clark 4992 (AAU!, MO!); Area Nacional de Recreación “Cajas” Sayausi-Molleturo road W of Cuenca, 02°53'S, 079°59'W, 3910 m, 21 June 1989, Dorr 6391 (AAU!); Parque Nacional de Cajas, WNW of Cuenca, 02°52'S, 079°09'W, 3450 m, 28 December 1979, Holm-Nielsen 20927 (AAU!); Parque de Recreación Cajas, 4000–4100 m, 02 September 1983, Jaramillo 7185 (AAU!, GB, QCA!); Parque Reacreacional Cajas, Strasse von Cuenca nach Morlleturo, 3900 m, 14 March 1991, Kessler 2746B (GOET!); Cuenca-Molleturo road ca. 5 km W of pass in Las Cajas, 02°49'S, 079°16'W, 3350 m, 01 May 1992, Lægaard 102646 (AAU!, GOET!, QCA!); Parque Nacional de Las Cajas, along road Soldados-Angas, in pass app. 13 km from Soldados, 02°53'S, 079°17'W, 4000 m, 02 May 1992, Lægaard 102691 (AAU!, GOET!, QCA!); 102696 (AAU!, QCA!); Páramo de las Cajas W of Cuenca, 02°47'S, 079°14'W, 4000–4150 m, 02 September 1984, Lægaard 52870 (AAU!, QCA!); 52878 (AAU!, MO!, QCNE); 52885 (AAU!, MO!, QCNE); 52888 (AAU!); 52891C (AAU!); Páramo de Soldados SW of Cuenca, 02°53'S, 079°17'W, 3700–3800 m, 24 October 1984, Lægaard 53243 (AAU!); Páramo de Soldados, SW of Cuenca, 02°53'S, 079°18'W, 3750–3850 m, 03 March 1985, Lægaard 53800 (AAU!, MO!); Páramo de Cajas, W of Cuenca, along new road, ca. 6–8 km W of pass, 02°48'S, 079°17'W, 3800 m, 31 March 1985, Lægaard 53935 (AAU!, QCA!); Páramo de Soldados, 02°53'S, 079°18'W, 3700–4000 m, 28–29 August 1985, Lægaard 55098 (AAU!); 55098C (AAU!); 55098D (AAU!); 55113 (AAU!); 55114A (AAU!); 55114B (AAU!); Páramo de Soldados-Angas, at highest point of road, 02°52'S, 079°17'W, 4000 m, 14 February 1988, Lægaard 70122 (AAU!, MO!); Area Nacional Recreacional Cajas, sector Llavinco, 02°50'S, 079°20'W, 3450–3550 m, 09 January 1991, León 2606 (USM!); Parque Nacional Cajas, km 32.1 desde redondel Cuenca-Molleturo, sendero este alrededor de Laguna Toreadora, 3850–3870 m, 08 January 2003, Ulloa 1013 (BRIT, HA, K, MO!, QCNE, US!); 1014 (HA, MO!, NY, QCNE); Parque Nacional Cajas, km 28 redondel Cuenca-Molleturo, sendero izquierdo Laguna Patoquinoas, 3730–3800 m, 12 January 2003, Ulloa 1130 (HA, ILLS, MO!); Parque Nacional Cajas, km 35 Cuenca-Molleturo, Centro de Información, Laguna Toreadora sendero oeste, 3880–3890 m, 16 January 2003, Ulloa 1234 (HA, ILLS, MO!, QCNE). Molleturo, Páramo de las Cajas, W of pass, 02°46'S, 079°15'W, 3700 m, 27 August 1985, Lægaard 55047 (AAU!, MO!, QCA!); Area Nacional Recreacional Cajas, sector La Toreadora, 02°50'S, 079°20'W, 3950 m, 12 January 1991, León 2624 (USM!); Area nacional Recreacional Cajas, sector La Toreadora, 02°50'S, 079°20'W, 3800 m, 13 January 1991, León 2651 (QCA!, USM!); Carretera Sayausi-Molleturo km 10–31, Parque Recreacional Las Cajas, 02°50'S, 079°15'W, 3350–3950 m, 28 November 1992, Romoleroux 1482 (AAU!, QCA!). San Antonio, 3–5 km W of pass at Las Cajas, W of Cuenca, 02°40'S, 079°14'W, 3800–4000 m, 22 October 1984, Lægaard 53199 (AAU!); Las Cajas, near Laguna Toreadora, 02°43'S, 079°12'W, 3900 m, 13 September 1983, Larsen 45141 (AAU!, QCA!). San Joaquin, Páramo de Soldados SW of Cuenca, 02°53'S, 079°17'W, 3700–3800 m, 24 October 1984, Lægaard 53235; 53235B; 53235D; 53235F; 53235H ; 53245; 53246 (AAU!); between Cuenca and Soldados, 02°57'S, 079°10'W, 2800–3000 m, 28 August 1985, Lægaard 55081 (AAU!); at Soldados, 02°57'S, 079°14'W, 3200–3400 m, 28 August 1985, Lægaard 55084 (AAU!); Páramo de Soldadas-Angas, at highest point of road, 02°52'S, 079°17'W, 3950–4050 m, 14 February 1988, Lægaard 70101 (AAU!); Páramo de Soldadas-Angas, at highest point of road, 02°52'S, 079°17'W, 3200–3300 m, 14 February 1988, Lægaard 70101A (AAU!); 70101B (AAU!); 70101C (AAU!); 70101D (AAU!). Sayausi, Parque Nacional de Cajas, WNW of Cuenca, 02°52'S, 079°09'W, 3450 m, 28 December 1979, Holm-Nielsen 20926 (AAU!); Páramo de las Cajas W of Cuenca, 02°47'S, 079°14'W, 4000–4150 m, 02 September 1984, Lægaard 52879; 52886; 52890; 52891; 52891A; 52891B; 52891D (AAU!); Cuenca–Area Recreacional Las Cajas, 26–30 km de Cuenca, 02°50'S, 079°06'W, 3360–3500 m, 17 November 1991, Romoleroux 1187 (AAU!, QCA!). Zurucucho, Canton Cuenca, 3200 m, 11 August 1978, Boeke 2622 (AAU!); ca. de la laguna La Toreadora, 3850 m, 26 December 1997, Burnham 3007 (QCA!); Dudahuaycu, Mazán, 3300 m, 28 May 1994, Chacón 211 (QCA!); Cantón Cuenca, collection made along río Patul from the Comuidad Baute Laguna Patul, watershed of río Patul, 3500–4200 m, 05 February 2001, Clark 6229 (QCA!); Parque Nacional Cajas, morenas ca. de la Laguna Toreadora, 4025 m, 15 November 2000, Endara 520 (QCA!); Parque Nacional Cajas, morrenas cerca de la Laguna de Soldados, 3830 m, 17 November 2000, Endara 564 (QCA!); ca. 10 km W of Sayausid, 3300 m, 04 November 1982, Harling 20218 (AAU!, GB); above Sayausi at first bridge over Río Tomebamba, 3200 m, 03 March 1985, Harling 22671 (AAU!, GB, QCA!); Páramo de Cajas, versant oriental; zone très humide; relique forestière dégradée, 3650 m, 10 April 1989, Huttel 1668 (QCA!); Páramo de Cajas, versant oriental, zone très humide, 3350–3950 m, 14 April 1988, Huttel 995 (QCA!); carretera Cuenca–Sayausid-Area de Recreación Cajas, 3900 m, 16 August 1987, Jaramillo 9898 (MO!); Parque Nacional Cajas, near headquarters on cuenca-Guayaquil road, 3900 m, 12 March 1991, Kessler 2746 (QCA!); Parque Recreacional Cajas, Strasse von Cuenca nach Molleturo, 3900 m, 14 March 1991, Kessler 2746A (GOET!); Páramo de Soldados, 3700 m, s.d., Lægaard 55096 (QCA!); 55114 (QCA!); at bridge 2 km below Soldados, 3200 m, s.d., Lægaard 70082 (QCA!); at bridge 2 km below Soldados, 3200 m, s.d., Lægaard 70083 (QCA!); s.d., León 2527 (QCA!); colección en parcela del bosque, arriba del lago Dos Chorreras, 3940 m, 05 July 1995, León 3541 (QCA!); arriba de laguna Chorreras, 3940 m, 05 July 1995, León 3542 (AAU!, QCA!); colección en bosque en la base del valle de Cajas cerca del hotel Dos Chorreras y en la ladera SO de la propiedad Dos Chorreras, 3400 m, 06 July 1995, León 3577 (QCA!); Vertiente oriental, 3100 m, 07 July 1995, León 3611 (QCA!); Área recreacional Cajas, 4000 m, 21 September 2000, Lizarzaburu 24 (QCA!); Fierroloma. Zorrocucho, ribera de Río Taitachugo, 3400 m, 20 May 1997, Minga 125 (QCA!); Totorococha-Mazan valley, 3500–4000 m, 12 September 1987, Ramsay 507 (QCA!); Parque Nacional Cajas, 3850–3900 m, 10 September 2001, Romoleroux 4028 (QCA!); Area de Recreación Cajas. km 1 de la via Miguir-Naranjal, 3500, 16 August 1987, Romoleroux 404 (QCA!); Hacienda Gulag, Masan, 3000–3200 m, 17 August 1987, Romoleroux 417 (QCA!); carretera Soldados-Angas, 3620 m, 04 April 2007, Romoleroux 4459 (QCA!); Bosque San Luis, 3939 m, 20 August 2008, Romoleroux 5108 (QCA!); 5127 (QCA!); carretera Molleoto Naranjal, parches de bosque fuera del parque nacional Cajas, 3939 m, 21 August 2008, Romoleroux 5157 (QCA!); Baños, 3300 m, 17 July 2006, Salgado 165 (QCA!); Cajas, 3725–3830 m, 24 June 1999, Smeets 432 (QCA!); Río Machangara, NW Cuenca, 3300–3400 m, 17 September 1967, Sparre 18568 (AAU!, S); s.d., Valverde 912 (MO!); carretera Sayausí-Quinona-Tres cruces, Area recreacional Cajas, 3500–4050 m, 10 April 1987, Zak 1894 (AAU!). Bolívar: upper west mountain Chimborazo, 3500–4000 m, 19 June 1887, Lehmann 4457 (MO!). Cañar: Vía Queseras-Rumiloma (Fund. Cordillera Tropical), 3353 m, 03 October 2006, Salgado 1181 (QCA!). Carchi: Espejo, parche de bosque alrededor de laguna Rasococha, 00°44'N, 078°04'W, 3600 m, 09 November 1993, Palacios 11897 (AAU!, MO!, QCNE). Chimborazo: Pungala, Near Alao, along Río Alao, 01°52'S, 078°30'W, 3200–3400 m, 21–22 September 1985, Lægaard 55295 (AAU!). Riobamba, Reserva Faunistica Chimborazo, 01°32'41"S, 078°53'05"W, 4100 m, 01 June 2006, Caranqui 1541 (CHEP, MO!); 3350–3500 m, 01 March 1944, Acosta-Solís 7524 (F!); 3750 m, s.d., Acosta-Solís 7696 (F!); 4000 m, s.d., André 3933 (F!, US!); San Juan, Chimborazo, 4350 m, 05 November 2013, Cardoso 4262 (QCA!); San Juan. Pasguazo Sambrano, 4100 m, 31 October 2013, Cardoso 4266 (QCA!);carretera Penipe a Utuñac Paramito, 2800 m, 07 April 2008, Jaramillo 26496 (QCA!); Sector Utuñac, Pijipamba, 3250–3330 m, 03 December 2008, Jaramillo 28123 (QCA!); Sector Utuñac, Pijipamba, 2800 m, 04 December 2008, Jaramillo 28132 (QCA!); E of Cordillera, 3400 m, s.d., Rimbach 14 p.p. (F!, NY, US!); 3400 m, s.d., Rimbach 156 (US!); s.d., Rimbach 498 (S); Vía Chambo-Guayllabamba-Aloa, 2900–3000 m, 09 August 1987, Romoleroux 366 (NY, QCA!). Imbabura: 4000–4300 m, s.d., Hirsch E-113 (NY). Loja: Manu, Cerro de Arcos W of road Manu-Zaruma, 03°34'S, 079°28'W, 3250–3600 m, 14 September 1999, Lægaard 20601 (AAU!, MO!). Napo: 3 km E of Paso de la Virgen on road Pifo-Papallacta, 3950–4050 m, 06 February 1985, Lægaard 54450 (QCA!); Parque Nacional Llanganates, 12 February 2009, Salgado 820 (QCA!). Pichincha: Cotogchoa, Volcán Pasochoa, Páramo and forest remains, 00°27'S, 078°30'W, 3500 m, 16 September 1985, Lægaard 55269A (AAU!, MO!); 55278 (AAU!, MO!); Bosque Protector Pasochoa, 30 km SE de Quito, 00°27'S, 078°28'W, 2850–3900 m, 08 September 1986, Romoleroux 161; 171 (AAU!, MO!, QCA!). El Chaupi, road El Chaupi-Iliñiza, 00°37'S, 078°40'W, 3200–3700 m, 20 June 1985, Lægaard 54547 (AAU!, QCA!); 54548 (AAU!, MO!); Volcán Iliñiza, N-side, 00°38'S, 078°41'W, 4200–4300 m, 20 June 1985, Lægaard 54554; 54555 (AAU!, MO!, QCA!). Rumiñahui, Bosque Protector Pasochoa, 00°22'S, 078°27'W, 3870–3900 m, 17 November 1990, Cerón 12323 (MO!). Rumipamba, Volcán Pasochoa, 00°27'S, 078°30'W, 2900–3300 m, 16 September 1985, Lægaard 55265 (AAU!, GOET!, MO!). Tambillo, Volcán Pasochoa, above house of Fundación Natura, 00°27'S, 078°31'W, 2800–3300 m, 27 April 1985, Lægaard 54176 (AAU!, MO!, QCA!); Volcán Pasochoa, 00°27'S, 078°30'W, 3500 m, 16 September 1985, Lægaard 55273 (AAU!, MO!). s.d., Holmgren 962 (S); Volcán Iliñiza, N-side, 4200–4300 m, 20 June 1985, Lægaard 54557 (QCA!); Volcán Pasochoa, Páramo and forest remains, 3500 m, 16 September 1985, Lægaard 55266; 55269B; 55274 (QCA!); Bosque Protector Pasochoa, 30 km SE de Quito, 2850 m, 29 October 1988, Paz 105 (MO!, QCA!); Faldas del Pasochoa, colección al Sur-Oeste, 3800 m, 03 March 1980, Raza 167 (AAU!); Bosque Protector Pasochoa, 30 km SE de Quito, 2850–3900 m, 17 July 1986, Romoleroux 141 (AAU!, QCA!); 162; 164; 166; 295 (AAU!, QCA!); Pasochoa, 3556 m, 20 August 2008, Romoleroux 5367 (QCA!); Volcán Rumiñahui, 4000 m, 19 December 2008, Salgado 595 (QCA!). Tungurahua: Mocha, Parroquia Pinguili, Reserva Faunístic del Chimborazo, pared de valle en U, 2 km antes de la Base del Lado Oriental del Caryguayrazo, cerro Pocacochas, páramo de Salasaca entrando por Mocha, 01°24'S, 078°45'W, 3860 m, 02 July 1992, Cerón 19203 (MO!). Pilaguin, Sabanza, about 5 km SE of Yatzapuzan, 01°19'S, 078°46'W, 3950–4050 m, 21 December 1982, Brandbyge 42024 (AAU!, MO!); Río Negro, Cordillera de Llanganates, loma between Río Topoand Río Verde Grande, 3.5 km NW of Cerro Hermoso, 01°12'S, 078°18'W, 4000 m, 10 November 1980, Holm-Nielsen 28297 (AAU!); Cordillera de Llanganates, NW of saddle between Río Topo and Río Verde Grande on W slope of Cerro Hermoso, 2.5 km from summit, 01°13'S, 078°18'W, 3950 m, 10 November 1980, Holm-Nielsen 28330 (AAU!); 28371 (AAU!); Cordillera de los Llanganates, at Río Verde Grande at base of Cerro Hermoso, 2 km WSW of the summit, 01°13'S, 078°18'W, 3800 m, 11 November 1980, Holm-Nielsen 28403 (AAU!); 28641 (AAU!); Cordillera de los Llanganates, loma 2.5 km W of Cerro Hermoso, 01°13'S, 078°18'W, 3800 m, 12 November 1980, Holm-Nielsen 28662 (AAU!); Quinuales, 01°13'18"S, 078°18'16"W, 3890 m, 15 February 2010, Romoleroux 5525 (MO!, QCA!, QCNE); 5529 (MO!, QCA!, QCNE); 5533 (MO!, QCA!, QCNE). Río Verde, Cordillera de los Llanganates, at Río Verde Grande at base of Cerro Hermoso, 2.5 km SW of the summit, 01°14'S, 078°18'W, 3700 m, 12 November 1980, Holm-Nielsen 28538 (AAU!); 28599 (AAU!); 28609 (AAU!). San Fernando, Quebrada Huarcusacha, 01°15'S, 078°47'W, 3800–3900 m, 27 January 1983, Brandbyge 42040 (AAU!, MO!); Near Calamaca, app. 20 km W of Ambato along old road Ambato-Guaranda, 01°16'S, 078°48'W, 3400–3900 m, 22 June 1985, Lægaard 54569 (AAU!, QCA!); 54574 (AAU!, MO!, QCA!); 54576 (AAU!, MO!, QCA!). Santiago de Píllaro, Parque Nacional Llanganates, slopes of metamorphic rock, west of Cerro Hermoso, near saddle between headwaters of Río Verde and Río Topo, 01°11'40"S, 078°19'34"W, 3950 m, 12 November 1999, Neill 11944 (MO!, QCNE); 3500 m, s.d., Acosta-Solís 8736 (F!); 4200 m, s.d., Asplund 8464 (S, WIS); Páramo de Yatsaputzan, 3600 m, 05 February 2010, Caranqui 1912 (QCA!); Tamboloma, 3721 m, 29 April 2012, Caranqui 2052 (QCA!); Minza mountain Travesia de Utañag, 3600 m, s.d., Jameson s.n (US!, K); 3400 m, s.d., Penland 420 (F!, US!); Entrando por Baquerizo Moreno hacia el sector de Lagartococha, 3270 m, 01 March 2015, Pérez 8424 (QCA!); Carretera Mocha-Hda. Atillo, 3000 m, 25 April 1988, Romoleroux 567 (AAU!, MO!, QCA!); 570 (AAU!, QCA!); Sendero El Triunfo-Los Llanganates, localidad El Playón, 3600–3800 m, 02 March 1989, Romoleroux 681 (AAU!, MO!, QCA!); 3200 m, s.d., Rimbach 26 (F!); s.d., Stübel 201 (MO!).

Polylepis simpsoniae T.Boza & M.Kessler, sp. nov.

Figs 57, 58

Diagnosis

The species differs from Polylepis weberbaueri Pilg. in the smaller, broadly ovate leaflets (0.9–1.6 × 0.4–1.1 cm) and shorter inflorescences (2.5–5.5 cm long) bearing 3–5 flowers, with each flower having 11–13 stamens.

Figure 57. 

Polylepis simpsoniae T.Boza & M.Kessler A leaves B upper leaf surface C leaves D habit E lower leaf surface. Scale bars: 1 cm (A–E). Photographs by T.E. Boza E.

Type

Ecuador: Cañar: along Páramo-road to Manu W of Cañar, 02°33'S, 79°02'W, 3300–3700 m, 20 June 1988, S. Laegaard 71564 (holotype: QCA!; isotype: AAU!).

Figure 58. 

Polylepis simpsoniae T.Boza & M. Kessler A flowering branch B stipular sheaths C fruit D upper leaf surface E lower leaf surface (A Romoleroux 589 B Laegaard 102679 C Laegaard 55087 D, E Laegaard 70084). Scale bars: 2 cm (A); 5 mm (C); 3 cm (D, E). Photographs by T. E. Boza E.

Description

Trees 1–8 m tall. Leaves slightly congested at the branch tips, imparipinnate with 2–3 pairs of lateral leaflets, obtrullate in outline, (2.3–)2.8–5.8 × (1.5–)1.9–3.3 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair (0.9–)1.3–1.6 × (0.4–)0.7–1.1 cm; margin entire or slightly crenate with 2–4 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.5–0.7 mm long. Inflorescences pendant, (2.5–)3.7–3.9(–5.5) cm long, bearing 3–5 flowers; floral bracts 3.3–6.1 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers (6.1–)6.7–9.1 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 11–13, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.8–3.3 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 2.4–5.8 × 5.1–7.5 mm including spines. Diploid.

Distribution, habitat, and ecology

Polylepis simpsoniae occurs in southern Ecuador (Cañar and Azuay) (Fig. 61). It grows on relatively dry slopes at 2500–3800 m elevation, where it often co-occurs with P. reticulata. When they co-occur, P. simpsoniae tends to occur at lower elevation (maximum probability of occurrence at 3300–3700 m) than P. reticulata (3800–4000 m) (Montalvo et al. 2018).

Etymology

We name the species in honor of Beryl B. Simpson (1942–), professor emeritus in the Department of Integrative Biology at the University of Texas at Austin, who, apart from her important contributions to the knowledge of Polylepis (Simpson 1979, 1986), has conducted remarkable research on tropical angiosperms.

Conservation status

Based on 15 collecting localities, the estimated EOO is 12,905 km2, and the AOO is 92 km2. It has been collected in Cajas National Park, but populations there are heavily fragmented and degraded. Indeed, many P. simpsoniae forests occur at low elevations outside of the protected area where they are subject to continuing fragmentation and habitat degradation from livestock grazing and firewood extraction. We assess P. simpsoniae as Endangered (A1, B1a+B2a, C2a).

Notes

Polylepis simpsoniae was treated as P. weberbaueri by previous authors (e.g. Simpson 1979; Romoleroux 1996), including within P. weberbaueri populations from central Ecuador and northern Peru. However, based on its distinct morphology and ecology, this taxon should be recognized as different from P. weberbaueri. Polylepis simpsoniae resembles P. weberbaueri in having 2–3 leaflet pairs and same type and density of hairs, but it has broadly ovate leaflets and smaller (0.9–1.6 × 0.4–1.1 cm) leaflets than P. weberbaueri, which has elliptic leaflets 1.6–2.1 × 0.6–0.9 cm. Further, P. simpsoniae has shorter inflorescences (2.5–5.5 cm) bearing 3–5 flowers, with each flower having 11–13 stamens, whereas P. weberbaueri has longer inflorescences (8.2–9.7 cm) bearing 9–11 flowers, with each flower having 19–21 stamens.

Specimens examined

Ecuador. Azuay: Baños, Parque Nacional de Las Cajas, along road Soldados-Angas app. 2 km above Soldados, 02°56'S, 079°12'W, 3480 m, 02 May 1992, Lægaard 102679 (AAU!, QCA!). Cuenca, Area Nacional de Recreación Cajas, collection made along Río Patul from the Comunidad Baute/Laguna Patul (watershed of Río Patul), 02°33'S, 079°21'W, 3500–4200 m, s.d., Clark 6229 (QCA!, QCNE, US!). Jimbilla, along road Cuenca–Soldados, 03°50'S, 079°09'W, 3000–3300 m, 03 March 1985, Lægaard 53795 (AAU!, MO!). San Joaquin, from Soldados eastwards along the road until Hda. San Vicente (west of Cuenca), 02°56'S, 079°10'W, 3200–3300 m, 05 January 1981, Balslev 1546 (AAU!, NY, QCA!); Parque Nac. de Las Cajas, at entrance to the park at Soldados, 02°56'S, 079°13'W, 3900 m, 02 May 1992, Lægaard 102677 (AAU!, GOET!); Páramo de Soldados, SW of Cuenca, 02°57'S, 079°14'W, 3020 m, 24 October 1984, Lægaard 53234 (AAU!, MO!); between Cuenca and Soldados, 02°57'S, 079°10'W, 2800–3000 m, 28 August 1985, Lægaard 55082 (AAU!); at Soldados, 02°57'S, 079°14'W, 2800–3000 m, 28 August 1985, Lægaard 55083 (AAU!); 55087 (AAU!, GOET!, MO!); at bridge 2 km below Soldados, 02°56'S, 078°13'W, 3200 m, 14 February 1988, Lægaard 70082 (AAU!, QCNE); 70084; 70085 (AAU!, MO!); cerca al Río Yanuncay, carretera via San Joaquin-Soldados Angas, 02°56'S, 079°13'W, 3100 m, 07 April 2007, Romoleroux 4445 (CHEP, ECUAMZ, QCA!). Sayausi, Las Cajas National Park. Wet páramo near roadside, 02°50'S, 079°12'W, 3500 m, 19 September 1983, Brandbyge 42269 (AAU!, MO!, QCA!); from Soldados E along the road until Hcda. San Vicente (W of Cuenca), 3200–3300 m, 05 January 1981, Balslev 1546 (QCA!); Zurucucho, Cantón Cuenca, Valley bottom, along rivers, 3200 m, 11 August 1978, Boeke 2622 (QCA!); route de Cuenca à Angas, páramo de Cajas, peu au dessus du hameau de Soldados, 14 km en desous du col sur le versant intérieur, 3250 m, 05 October 1988, Huttel 1136 (QCA!); Páramo de Soldados, SW of Cuenca, 3320 m, 24 October 1984, Lægaard 53234 (QCA!); between Cuenca and Soldados, 2800–3000 m, 28 August 1985, Lægaard 55082 (QCA!); at Soldados, 3200–3400 m, 28 August 1985, Lægaard 55083 (QCA!); at Soldados, 3200 m, 28 August 1985, Lægaard 55087 (QCA!); at bridge 2 km below Soldados, 3200 m, 14 February 1988, Lægaard 70084 (QCA!); Parque Nacional Cajas, 3850–3900 m, 10 September 2001, Romoleroux 4028 (QCA!); Est. San Pedro near Canar on steep slopes, 02 January 1977, Simpson 8532 (US!, USM!); 8532a (USM!); Cajas, Río Blanco, 3620 m, 28 August 1999, Smeets 791 (QCA!). Cañar: Gualleturo, along Páramo–road to Manu W of Cañar, W of pass, 02°33'S, 079°02'W, 3700 m, 20 June 1988, Lægaard 71561; 71564 (AAU!, QCA!); 71567 (MO!). Ingapirca, Comunidad San Isidro de Vendeleche, 02°32'S, 078°50'W, 3200 m, 04 March 1983, Brandbyge 42085 (AAU!, MO!, NY); Ingapirca Parish, Silante, 02°29'S, 078°49'W, 3450 m, 01 January 1992, Kohn 1526 (MO!). Zhud, along road to Culebrillas ca. km 6–10, 02°26'S, 078°57'W, 3400–3500 m, 04 February 2000, Lægaard 21006 (AAU!, MO!); at the antennas of Culebrillas ca. 17 km from Panamericana, 02°26'S, 078°57'W, 4000 m, 04 February 2000, Lægaard 21031 (AAU!, MO!). Guapán, 3525 m, 28 November 2000, Endara 760 (QCA!); along páramo road to Manu W of CaÒar. W of pass, 3300–3700 m, 20 June 1988, Lægaard 71561 (QCA!); Pimo, entre Oyacshi y Zhud, 3250 m, 13 October 1987, Romoleroux 392 (AAU!, NY, QCA!); Desde Cañar, km 10.5, Cerro Caucay, 3450 m, s.d., Romoleroux 586 (AAU!, QCA!); Oeste de Cañar, Km 10.5, Cerro Cuacay, 3450 m, 27 April 1988, Romoleroux 587 (AAU!, MO!, QCA!); 589 (AAU!, QCA!); s.d., Rose 22722; 22733; 23792 (NY, US!); Cuenca del Río Dudas (Fund. Cordillera Tropical), 3230 m, 17 October 2006, Salgado 1292 (QCA!). Chimborazo: Chimborazo/Cañar: between Santa Rosa and Joyagshi, near Tipococha, 3500 m, s.d., Camp E-4088 (F!, NY, US!). Tungurahua: Bellavista, 3700 m, 05 December 2009, Caranqui 1907 (QCA!).

Polylepis weberbaueri Pilg., Bot. Jahrb. Syst. 37: 535. 1906.

Figs 59, 60

Type

Peru. Ancash: from Yanganuco to Yungay, 3800 m, 16 June 1903, Weberbauer 3287 (holotype: B destroyed; photos at F, GH, MO!, NY).

Figure 59. 

Polylepis weberbaueri Pilg A fruits B upper leaflet surface C lower leaflet surface D leaves E stipule sheaths F flowers G flowering branch H bark (A, D–G Boza & Urquiaga 3021 B, C, H Boza & Urquiaga 3017). Scale bars: 2 cm (A); 1 cm (B–D); 2 mm (E); 3 mm (F); 3 cm (G). Photographs B, C, F–H E. G. Urquiaga F. A, D, E T.E. Boza E.

Description

Trees 1–14 m tall. Leaves slightly congested at the branch tips, imparipinnate with 2–3 pairs of lateral leaflets, obtrullate in outline, (3.2–)5.2–5.8 × (2.7–)3.2–3.5 cm; rachises densely tomentose, points of leaflet attachment with a tuft of long, lanate hairs; stipular sheaths apically acute with spurs, densely lanate on the outer surfaces; leaflets elliptic in outline, second pair from the terminal leaflet the largest, one of this pair 1.6–2.1 × 0.6–0.9 cm; margin entire or slightly crenate at apex with 3–4 teeth, apically emarginate, basally unequally cordate; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose with whitish hairs 0.4–0.5 mm long. Inflorescences pendant, 8.2–9.7 cm long, bearing 9–11 flowers; floral bracts 5.4–7.5 mm long, narrowly triangular, densely lanate on the outer surface; rachises tomentose. Flowers 8.6–10.4 mm diam.; sepals 4, ovate, green, densely tomentose outside; stamens 19–21, anthers orbicular, with a dense tuft of straight white hairs on the upper half; styles fimbriate, 2.7–3.2 mm long. Fruits turbinate, with variable numbers and placement of flattened spines, densely villous; 4.2–4.9 × 4.8–5.3 mm including spines. Diploid.

Figure 60. 

Polylepis weberbaueri Pilg A flowering branch B upper leaf surface C lower leaf surface D stipular sheaths E fruit (A Smith 10608 B–E Boza 3017). Scale bars: 5 cm (A); 3 cm (B, C); 3 mm (E). Photographs by T. E. Boza E.

Distribution, habitat and ecology

Polylepis weberbaueri is distributed in northern Peru in Ancash, Huánuco and Lima (Fig. 61). It occurs in dry and cold Andean habitats at 3500–4970 m elevation. Some stands of P. weberbaueri occur in semi-humid areas mixed with Gynoxys, Oreocallis, Alnus, Berberis and Buddleja, but it can also be found in large, homogeneous stands with dense vegetation cover and very robust trees (Sevillano-Ríos et al. 2011). It often co-occurs with P. albicans, but P. weberbaueri tends to occur at higher elevations (ECOAN 2005; Fuentealba and Sevillano 2016; Sevillano-Ríos and Rodewald 2017; Morales et al. 2018). In a study in Huascarán National Park, seedling density of P. weberbaueri increased with elevation and decreased with solar radiation (Morales et al. 2018). These forests also support the hemiparasite Tristerix chodatianus (Patschovky) Kuijt (Loranthaceae) at over 4400 m elevation (ECOAN 2005; Sevillano-Ríos et al. 2011). Polylepis weberbaueri forests at higher elevations (> 4000 m) harbor some of the most specialized and endangered bird species (Sevillano-Ríos et al. 2011; Sevillano-Ríos and Rodewald 2017).

Figure 61. 

Geographical distribution of the species of section Reticulatae.

Conservation status

The EOO is estimated as 15 388 km2 and AOO as 224 km2. The species has been collected in 39 locations. It is protected within Huascarán National Park and was categorized as VU (SERFOR 2006). It is subject to reforestation activities in Huascarán National Park (Fuentealba and Sevillano 2016). We assess P. weberbaueri as Vulnerable (B1a B2a).

Notes

Polylepis weberbaueri can be distinguished from the most similar species P. occidentalis by the number of lateral leaflet pairs (2–3 versus 3–5), inflorescence length (8.2–9.7 cm versus 2.4–6.7 cm), style length (2.7–3.2 mm versus 1.5–2.0 mm) and number of stamens (19–21 versus 9–15).

Specimens examined

Peru. Ancash: Bolognesi, Pachapaque, Distr de Aquia, 3900 m, 01 August 1972, Cerrate 2 (USM!); entre Llamac y Jahuacocha, 4900 m, 29 May 1954, Cerrate 2314 (USM!); road from Abra Janashalla down to Huallanca, below Huansalá, 09°52'05"S, 076°59'27"W, 3390 m, 08 October 2007, Weigend 8810 (USM!). Carhuaz, Sonquenua, Shilla, 3950 m, 21 December 1989, Arce 187 (MO!); Huascarán National Park. Quebrada Ishinca, north side of valley, 09°23'S, 077°26'W, 4110–4350 m, 15 July 1985, Smith 11169 (MO!, USM!); Huascarán National Park, Quebrada Ishinca, south side of valley, 09°23'S, 077°26'W, 4200–4260 m, 17 July 1985, Smith 11236 (AAU!, F!, MO!, USM!); Huascarán National Park. Quebrada Ulta, on road to Ulta Pass, WNW-facing, steep slope, 09°08'S, 077°32'W, 4280 m, 29 July 1985, Smith 11383 (MO!, USM!); 11659 (F!, MO!, USM!); Huascarán National Park, Quebrada Ishinca, 09°22'S, 077°25'W, 4400 m, 13 February 1985, Smith 9535 (MO!, USM!); 09°23'S, 077°27'W, 4100 m, 14 February 1985, Smith 9568 (AAU!, F!, MO!, USM!). Chavin de Huantar, Cordillera Blanca, Quebrada Pucavada (road between Huaraz and Chavin, on eastern side of pass), 09°40'S, 077°15'W, 4100 m, 16 February 1987, Boertmann 62 (AAU!); 64 (AAU!). Cusca, Cordillera Blanca, Misquicyucu 20 km east of Yanac towards Sihuas, top of the pass, 08°37'S, 077°45'W, 4000 m, 20 February 1987, Boertmann 74 (AAU!). Huantar, Quebrada Carhuascancha, Cordillera Blanca, 09°29'S, 077°15'W, 3900 m, 15 August 1988, Frimer 131 (AAU!); 133 (AAU!); 134 (AAU!). Huaraz, Feria de plantas medicinales de Huaraz, 3052 m, 01 July 1988, Amaro s.n (USM!); Quebrada Pitec, 4000 m, 30 October 1989, Arce 162 (MO!); Llaca, 09°28'52"S, 077°27'42"W, 3909 m, 08 November 2014, Boza 3021 (USM!, Z!); Rajacolta, 4420 m, 06 June 2015, Boza 3148; 3149 (USM!, Z!); Ulta, 4450 m, 07 June 2015, Boza 3150; 3151 (USM!, Z!); Quebrada Shallap, Cordillera Blanca, 09°31'S, 077°24'W, 4000 m, 10 August 1988, Frimer 16; 17; 4 (AAU!); Huascarán National Park, Quebrada LLaca, NW-slope of valley, 09°27'S, 077°27'W, 4200–4400 m, 24 May 1985, Smith 10783 (MO!, USM!); Huascarán National Park, Quebrada Llaca, valley bottom and north side of valley, 09°27'S, 077°27'W, 4090 m, 13 July 1985, Smith 11143; 12432 (MO!, USM!); 8973 (AAU!, MO!, USM!); 9696 (MO!, USM!). Huari, 30 km N of Huari, 3960 m, 18 December 1979, Aronson 993 (F!, MO!); 3000 m, 15 August 1983, Basauri 3 (USM!); Cahuish, 09°41'30"S, 077°14'30"W, 4306 m, 08 November 2014, Boza 3017; 3018 (USM!, Z!); Chavín, antes del Tunel de Cahuish (Cuta Queñua), 3100–3200 m, 11 June 2002, Cano 12385 (MO!, USM!); 09°33'S, 077°10'W, 3500 m, 14 February 2006, Sayre 39 (USM!); Huascarán National Park, road to microwave tower passing Manto Mina, off Catac-Chavin road, 09°42'S, 077°15'W, 4400 m, 04 July 1985, Smith 10974 (MO!, USM!); Huascarán National Park, upper terrace, Quebrada Pachachaca a lateral valley of Quebrada Rurichinchay Bogs, 09°23'S, 077°17'W, 4040–4200 m, 13 June 1986, Smith 12586 (F!, MO!, USM!); Huascarán National Park. Catac-Chavin road, 44 km from Catac, 09°42'S, 077°13'W, 4200 m, 18 August 1984, Smith 8287 (MO!, USM!); Huascarán National Park, 0.25 km from Cahuish Tunnel, 09°41'S, 077°14'W, 4450 m, 23 December 1984, Smith 8752 (F!, MO!, USM!). Huaylas, Laguna Parón, 3860–4000 m, 15 October 1999, Cano 10023 (USM!); Quebrada Paron, Cordillera Blanca (east of L. Paron), 08°58'S, 077°38'W, 4200 m, 16 August 1988, Frimer 23; 24; 26 (AAU!); Huascarán National Park, Quebrada Parón, 09°01'S, 077°43'W, 3500–3760 m, 08 May 1985, Smith 10608 (AAU!, F!, MO!, USM!); Huascarán National Park, Parón valley E of lake, 08°59'S, 077°38'W, 4250 m, 27 September 1985, Smith 11477 (F!, MO!, USM!); Huascarán National Park. Quebrada Santa Cruz at base of and entering Quebrada Artizonraju, 08°55'S, 077°36'W, 4300–4800 m, 16 January 1985, Smith 9308 (MO!, USM!); Huascarán National Park, environs of Hatuncocha, 08°52'S, 077°45'W, 4600 m, 12 March 1985, Smith 9982 (AAU!, F!, MO!, USM!); Huascarán National Park. between Huiscash and Mirador, 08°53'S, 077°46'W, 3960–4400 m, 12 March 1985, Smith 9988 (MO!, USM!). Pomabamba, Pumacocha, 4200 m, 11 December 1989, Arce 175 (MO!); Pumacocha, 4300 m, 11 December 1989, Arce 177 (MO!); Quenuarajra, 3600 m, 12 December 1989, Arce 182 (MO!). San Marcos, San Marcos. Distr. Ccolla Chica, 09°40'28"S, 077°03'10"W, 5600 m, 04 May 2008, Beltrán 6480 (USM!). Shilla, Quebrada Matará in Quebrada Ulta, Cordillera Blanca, 09°07'S, 077°32'W, 4250 m, 03 September 1988, Frimer 105; 106; 114 (AAU!). Sihuas, Distr. Cashapampa, Pasacancha, 08°35'01"S, 077°39'09"W, 3972 m, 03 February 2011, Gonzáles 1423 (USM!). Tarica, Quebrada Ishinca, Cordillera Blanca, 09°23'S, 077°28'W, 3950 m, 23 August 1988, Frimer 72 (AAU!). Yungay, Yanama, 3950 m, 05 November 1989, Arce 166 (MO!); Llanganuco, fuera del parque Huascarán, 3500 m, 29 May 1981, Cerrate 7769 (USM!); ca. 25 km NE of Yungay, slopes below Laguna de Llanganuco, 3380 m, 28 January 1983, Dillon 3117 (F!, MO!, USM!); slopes below Laguna de Llanganuco in quebrada de Llanganuco ca. 25 km above Yungay, 3900 m, 27 June 1966, Edwin 3829 (F!); Llanganuco, 3700–3800 m, 02 May 1961, Ferreyra 14377 (GOET!, MO!, USM!); 37 km east of Yungay, 4200 m, 05 April 1988, Renvoize 5084 (AAU!, MO!); Huascarán National Park, Llanganuco sector, Quebrada Demanda, side valley to Nevado Pisco, 09°01'S, 077°37'W, 4600–4800 m, 13 April 1985, Smith 10299 (MO!, USM!); Smith 8794 (MO!, USM!); Huascarán National Park. Quebrada Ranincuray, 08°59'S, 077°34'W, 4000–4300 m, 12 January 1985, Smith 9139 (AAU!, MO!, USM!). 4000 m, 24 August 1977, Antunez de Mayolo 330 (MO!, USM!); Cordillera Blanca, East of Yungay Lagunas de Llanganuco lake side, 3800 m, 05 April 1988, Renvoize 5067 (AAU!); 16 June 1903, Weberbauer 3287 (B, MO!). Huánuco: Huallanca, Huansala 10 km from Huallanca, 09°51'S, 076°56'W, 3700 m, 14 February 1987, Boertmann 48 (AAU!). Lima: Cajatambo, Cerro San Cristobal, 3950 m, 12 March 1990, Arce 206 (MO!); Raura, 4600 m, 05 April 1988, Rivas s.n (USM!). Oyon, Laguna Guengue Grande, Quichas, 4200 m, 11 January 1990, Arce 190 (MO!); Pueblo Quichas above Oyon, 10°36'S, 076°45'W, 4000 m, 26 February 1987, Boertmann 81; 82; 85; 87 (AAU!); Oyon, Laguna grande, 10°33'48"S, 076°44'25"W, 4005 m, 24 May 2015, Boza 3026; 30