Research Article
Research Article
Eithea lagopaivae, a new critically endangered species in the previously monotypic genus Eithea Ravenna (Amaryllidaceae)
expand article infoAntonio Campos-Rocha, Alan William Meerow§, Edimar Faria Menezes Lopes, João Semir, Juliana Lischka Sampaio Mayer, Julie Henriette Antoinette Dutilh
‡ Universidade Estadual de Campinas, Campinas, Brazil
§ USDA-ARS-SHRS, Miami, United States of America
Open Access


Eithea lagopaivae Campos-Rocha & Dutilh, sp. nov. is described as the second species of the formerly monotypic genus Eithea. It is characterized by a one flowered inflorescence, completely hollow scape, white or lightly magenta-striated flower that is enclosed by spathe bracts fused for more than the lower fifth of its length. Comments on its range, habitat, phenology, as well as photographs and illustrations are provided. In addition, a distribution map and an identification key for the two species of the genus are presented and anatomical and ecological differences compared. Known by only two small populations exposed to several types of threats and without any guarantee of protection, E. lagopaivae is considered a Critically Endangered (CR) species.


Eithea lagopaivae Campos-Rocha & Dutilh, sp. nov. é descrita como a segunda espécie do gênero previamente monotípico Eithea. Caracteriza-se por apresentar a inflorescência uniflora, escapo totalmente oco, flor alva ou com leves estrias magenta, protegida por brácteas espatáceas fundidas na base por mais de um quinto do seu comprimento. Comentários sobre a sua área de ocorrência, hábitat, dados de fenologia, fotografias e ilustrações são fornecidos. Adicionalmente, um mapa de distribuição e uma chave de identificação para as duas espécies do gênero são apresentados e suas diferenças anatômicas e ecológicas comparadas. Conhecida de apenas duas pequenas populações sujeitas a diversos tipos de ameaça e sem qualquer garantia de proteção, E. lagopaivae é considerada uma espécie Criticamente em Perigo (CR) de extinção.


Anatomy, Asparagales , Endemism, Hippeastreae, São Paulo


Anatomia, Asparagales , Endemismo, Hippeastreae, São Paulo


Eithea Ravenna (2002) was proposed as a monotypic genus with the transfer of Griffinia blumenavia K.Koch & C.D.Bouché ex Carrière, historically a species of somewhat uncertain classification. It was described from material collected in Santa Catarina state, Brazil, cultivated at the Berlin Botanical Garden and originally placed in the genus Griffinia Ker Gawl. (Carrière 1867) presumably because of the pseudopetiolate, evergreen leaves. Combinations for both Hippeastrum Herb. (Sealy 1937) and Amaryllis L. (Traub 1938) were subsequently proposed. Transfer to Hippeastrum was indicated due to perceived similarities with the flowers and seeds of H. reticulatum Herb. (Sealy 1937) while Traub (1938) proposed the transfer to Amaryllis, in line with his belief that the type specimen of Amaryllis belladonna L. was an American plant (see Goldblatt 1984, for full details of this controversy). Satô (1938) published a chromosome number of 2n = 77 for the species, which would be consistent with x = 11 chromosomes as a basic chromosome number for Hippeastrum (Naranjo and Andrada 1975, Flory 1977). Almost fifty years later, Traub (1983) proposed the restoration of the species in Griffinia based on the work of Arroyo (1982), who reported 2n = 20 chromosomes for the species.

A phylogenetic analysis of nrDNA ITS sequences resolved G. blumenavia as having a closer relationship to the genus Rhodophiala Presl, than with either Griffinia or Hippeastrum (Meerow et al. 2000). This work also reported a chromosome number of 2n = 18 for G. blumenavia, the number found in most Rhodophiala species (Satô 1942, Ficker 1951, Naranjo 1969, Flory 1977). Meerow et al. (2000) considered that these findings would justify the separation of G. blumenavia from Griffinia and Hippeastrum with recognition as a distinct monotypic genus. The authors of the current paper analyzed different individuals of the species and found the main somatic chromosome number of 2n = 18. However, a few cells from some individuals exhibited 19 to 20 chromosomes, perhaps explaining Arroyo (1982) report of 2n = 20. These additional smaller or supernumerary chromosomes are considered B-chromosomes (Jones and Rees 1982, Dutilh 1989, Ising 1990, Ising and Wide-Andersson 1991) due to their erratic behavior. Ravenna (2002) described the species as Eithea blumenavia (K.Koch & C.D.Bouché ex Carrière) Ravenna based on some morphological considerations, not on phylogeny nor chromosome number.

Currently, Eithea is positioned in tribe Hippeastreae, which includes Hippeastrum and Rhodophiala (Meerow et al. 2000, Oliveira 2012, García et al. 2014, 2017). In the same studies, Griffinia, sister of monotypic Worsleya, is included in the tribe Griffinieae Ravenna, a strongly supported clade. Eithea has some unusual morphological attributes for Hippeastreae, such as pseudopetiolate oblanceolate leaves with attenuate base, as well as globose seeds with elaiosome, features also found in Griffinia. However, testa of Eithea seeds contains phytomelanin, a typical trait of Hippeastreae, not found in Griffinia.

At the end of the 1990s, the researcher Celso do Lago Paiva discovered the new species in Piracicaba, São Paulo state, Brazil. Morphological, ecological and anatomical analyses conducted on material of the species over the past ten years have confirmed that it is an undescribed species of Eithea.

Material and methods

The following national and international herbaria with the most important collections of Brazilian Amaryllidaceae, particularly those from the state of São Paulo, were visited: BR, C, ESA, HRCB, IAC, K, MBM, MO, NY, RB, SP, SPF, SPSF, UEC, and US (acronyms according to Thiers 2017). The terminology used for the morphological description follows Radford et al. (1974), Meerow and Snijman (1998), and Stearn (2004), with minor modifications. In addition, comments on the conservation status of the taxon are provided as recommended by IUCN (2016). GeoCAT (Bachman et al. 2011) was used to calculate Area of ​​Occurrence (AOO) and Extent of Occurrence (EOO). Climatic data was obtained from Banco de Dados Climáticos do Brasil (EMBRAPA 2003) for the municipalities of Indaial (Santa Catarina) and Piracicaba (São Paulo). These two localities present collections of E. blumenavia and E. lagopaivae respectively. The map was drawn with ArcGIS 10.5 (ESRI).

For the morphological analysis, measurements were made on at least 15 individuals of each species, fresh plants and exsiccates. For the anatomical analysis, slides were prepared with fresh mature leaves of E. blumenavia and E. lagopaivae. At least five fully expanded and mature leaves of each species were fixed in Karnovsky (Karnovsky 1965) for 24 h, dehydrated in ethanol series (10%, 30%, 50% - 1 h each) and stored in 70% ethanol. Samples of leaves from both species were selected, encompassing the middle region of the pseudopetiole and the lamina, which was subdivided into midrib region and area between the midrib and margin. Infiltration was performed in plastic resin (Leica Historesin®) according to manufacturer’s instructions. Transverse and longitudinal sections of 7 µm thickness were obtained with manual rotary microtome (Leica®) and stained with 0.05% toluidine blue (Sakai 1973) in citrate buffer. Slides were mounted in synthetic resin “Entellan®” (Merck®) and images were obtained with an Olympus DP71 digital camera attached to an Olympus BX51 microscope.

Vouchers of the species and populations were deposited at UEC.

Results and discussion

Eithea lagopaivae Campos-Rocha & Dutilh, sp. nov.

Figures 1, 2


Eithea lagopaivae differs from E. blumenavia (Figure 3) by its smaller size, one flowered inflorescence (vs. 2–6, very rarely 1), a fully hollow scape (vs. solid in the lower fifth), terminated by spathe bracts fused for more than the lower fifth of their length (vs. free or fused up to the lower fifth), absence of bracteoles (vs. presence), white or only very lightly striated flowers (vs. strongly striated) and lateral and lower petals of similar width (vs. lateral petals up to twice the width of the lower).


BRAZIL. São Paulo: Piracicaba, sub-bosque de uma plantação comercial de Eucalyptus abandonada, 07 Dec 2016, A. Campos-Rocha 1654 (holotype: UEC!; isotypes: NA!, RB!).


Geophytic herb 12–25 cm tall. Bulb subterranean, globose to ovoid or obovoid, tunicate, whitish or with a thin grey-brownish outer tunic, 1.3–3.5 cm long and 1.2–3 cm diameter; neck formed by sheathing leaf bases up to 4.5 cm long and 3–8 mm diameter (occasionally very short to absent). Leaves 1–3(–4), suberect, dark green adaxially, pale green abaxially, frequently pseudopetiolate; pseudopetiole flattened adaxially, rounded abaxially, greenish, with reddish pigmentation near the base or throughout its length, up to 9.5 cm long, 2–5.5 mm wide; lamina linear, narrowly elliptic or oblanceolate to slightly falcate, apex acute, frequently asymmetric, base attenuate, margin flat, venation transverse reticulate (with short transverse veins between the longitudinal ones), midrib inconspicuous adaxially, prominent abaxially, 8–20.8 × 1.1–2.6 cm. Inflorescence one flowered; scape erect, cylindrical, slightly laterally compressed, hollow and fragile, greenish, sometimes with reddish pigmentation near the base, 7.8–30 cm long and 2.4–6 mm diameter, elongating and becoming decumbent with fructification; spathe bracts 2, tubular, fused in the basal 0.4–2.4 cm, apex acute, whitish, generally light rose colored at the tip before opening, turning papery, 1.7–3.8 cm long. Pedicels greenish, (0.3–)1.3–5.5 cm long, often elongating with fructification to 6.5 cm long. Perigone campanulate to infundibular, white (in bud white with a rose colored tip), usually with faint thin magenta striations on the sepals and petals, especially on the upper sepal, with greenish pigmentation near the base, mostly close to the midrib, 3–5.8 cm long; hypanthium greenish, 2–4.5 mm long, paraperigone of fimbriae 0.5–2 mm long at the throat. Sepals much wider than the petals, oblanceolate to obovate, the upper one wider and longer, apex acute, apicule subapical; upper 2.7–5.6 × 1–2.4 cm, apicule 0.8–2 mm long; lateral 2.5–5.4 × 0.6–2 cm, apicule 0.6–1.4 mm long. Petals oblanceolate, apicule inconspicuous or absent; lateral 2.5–5.5 × 0.6–1.4 cm; lower slightly narrower, 2.5–5.5 × 0.4–1.2 cm. Filaments 6, in four different lengths, inserted at the mouth of the hypanthium tube, shorter than limb segments, declinate-ascending, free portion white; upper episepal 1.1–2.5 cm long; lateral episepal 1–2.2 cm long; lateral epipetal 1.7–4 cm long; lower epipetal 1.6–3.8 cm long. Anthers oblong to oblong-reniform, dorsifixed, versatile, dehiscing longitudinally, 2.5–5 mm long before anthesis; pollen pale yellow. Ovary trilocular, obtuse trigonal, obovoid, greenish, 3.5–9 mm long and 3–8 mm diameter; 8–14 ovules per locule; ovules 0.6–1 mm long. Style declinate-ascending, white, occasionally with greenish pigmentation near the base, 2.6–5 cm long; stigma trifid, white, lobes already expanded when the flower opens, occasionally of different lengths, 1.5–4.5 mm long. Fruit capsule loculicidal, globose to globose-compressed trilobed, greenish when ripe, occasionally with reddish pigmentation, cream colored inner side, 1–2.5 cm long and 1.2–2.6 cm diameter. Seeds irregular, angular, with grey brownish to black testa containing phytomelanin, 3.5–6 mm long and 3–5.5 mm diameter, with wrinkled elaiosome up to 4.5 mm long.

Distribution, habitat and ecology

Eithea lagopaivae is known from only two small populations separated about 50 km, each composed of less than 50 individuals. The type population (Piracicaba) occurs in the understory of an abandoned Eucalyptus plantation, next to fragments of deciduous and semideciduous forest, where the Corumbataí river meets the Piracicaba river. The second is located in a small fragment of semideciduous forest, near the junction of the basins of the Piracicaba and Tietê rivers in the municipality of Tietê (Figure 4). Both fragments are located on gravelly soils of litholic limestone origin (Oliveira and Prado 1989). The region presents a well-defined seasonality, with total annual rainfall of 1230 mm and precipitation of 50 mm or less, for six months, during autumn and winter. During spring and summer, rainfall exceeds 100 mm for six months, reaching close to 250 mm in January (EMBRAPA 2003). Ants were observed removing elaiosomes from the seeds of E. lagopaivae in their natural habitat, indicating that these animals might be dispersal agents, as is known for Griffinia.


Eithea lagopaivae has been collected in bloom between October and January, and occasional blooming occurs until early March. Fruits have been observed from November.

Conservation status

With estimated AOO of 8 km2 and EOO of 13.7 km2, Eithea lagopaivae can be considered as Critically Endangered [CR, B1ab(iii) + B2ab(iii)], due to the low number of known locations (≤ 5) and decline in quality of habitat (IUCN 2016). In the municipality of Piracicaba, at the end of the year 2016, when the species was again visited, two small scattered groups were encountered ca. 500 meters apart. The smaller of the two groups was in a trash dump on the side of the wooded area, and the second in an area of ​​higher humidity, near a small stream. This fragment, on the edge of the urban sprawl of Piracicaba, is highly disturbed and subject to regular episodes of fire. The population of the Tietê municipality is in a slightly larger fragment of semideciduous forest with an impoverished understory, intense edge effects, with many lianas and invasive exotics. The area is located within a livestock breeding facility.


The epithet is a tribute to Celso do Lago Paiva, environmental analyst at ICMBio, who has collected the plant for the first time and has dedicated his life to the study and conservation of the flora of Brazil.

Additional specimens examined

BRAZIL. São Paulo: Piracicaba, 18 Mar 1999, J. Dutilh s.n. (UEC-170468!); 17 Nov 1999, J. Dutilh s.n. (UEC-174104!); 29 Nov 1999, J. Dutilh s.n. (UEC-174105!); em cultivo no Jardim Botânico Plantarum, Nova Odessa-SP, 10 Oct 2012, A. Campos-Rocha 810 (NA!, RB!, UEC!); em cultivo em Campinas-SP, 10 Oct 2013, A. Campos-Rocha & J. Dutilh 1165 (NA!, UEC!); plantação abandonada de Eucalyptus, 09 Oct 2016, A. Campos-Rocha & R.M. Goffi 1626 (UEC!); plantação de Eucalyptus abandonada, 20 Nov 2016, A. Campos-Rocha 1647 (NA!, UEC!). Tietê, 20 Nov 2001, J. Dutilh & L.C. Bernacci s.n. (UEC-170469!); L.C. Bernacci et al. 4483, fragmento de floresta semidecídua, 03 Mar 2017 (IAC!, UEC!).


Eithea lagopaivae and E. blumenavia form a clade with maximal support in all phylogenetic analyses performed by García et al. (2017). Eithea lagopaivae can be distinguished from E. blumenavia by a number of characteristics (Table 1). It is a smaller plant (ca. 12–25 cm), usually with 2-3 leaves, rarely 4, which are deciduous before the onset of winter. Eithea blumenavia however is evergreen, with 2-8 leaves, and up to 50 cm in height, although specimens of extremely reduced size are known, also with several flowers.

Eithea lagopaivae is known from an area originally of deciduous and semideciduous forests with a well-defined dry season. In turn, E. blumenavia is found in wetlands of the Atlantic rainforest, from the south of the state of São Paulo to eastern Santa Catarina (Dutilh 2010, Dutilh and Oliveira 2015) (Figure 4), especially in the coastal mountains. The region has some of the highest average annual rainfall (1650 mm) of any area of extra-Amazonian Brazil, distributed throughout the year, but more intensely during the summer, although with an average under 200 mm/month. From April to July, monthly averages are close to 100 mm (EMBRAPA 2003).

Eithea blumenavia is considered an Endangered (EN) species (MMA 2014).


The three most obvious anatomical characteristics differentiating the two species of Eithea are: 1. Margins and cortex of the pseudopetiole (Figure 5A–B); 2. Ornamentation and shape of the epidermal cells on the adaxial side of the leaf blades (Figure 5C–D); 3. Presence or absence of protrusions on the upper side of the blades in the region of the midrib (Figure 5I–J).

Cross section of pseudopetiole margins of E. lagopaivae are flatter, more laminar (Figure 5A, arrow) than those of E. blumenavia, which are angular (Figure 5B, arrow). The pseudopetiole is composed by chlorenchyma, aerenchyma and vascular bundles. In E. lagopaivae, 1–3 aerenchyma lacunae were found below the vascular bundles (Figure 5A), while in E. blumenavia several lacunae above and below the bundles could be observed (Figure 5B).

In the cross section of leaf lamina, epidermal cells were more elongated in E. lagopaivae and polyhedral in E. blumenavia (Figure 5C–D, respectively). We found periclinal thickening on the outer wall of the epidermal cells of both species as occurs in Hippeastrum puniceum (Lam.) Kuntze (Alves-Araújo et al. 2012). Ornamentation of the external periclinal epidermal cell wall of E. blumenavia (Figure 5D, arrow) was not found in E. lagopaivae (Figure 5C). Mesophyll of E. lagopaivae and E. blumenavia is composed of about 6–8 layers of chlorenchyma with arm-palisade cells (also called arm-cells, H-palisade or H-cells) (Figure 5E–F), which showed their typical morphology in paradermic sections (Figure 5G–H). Arm-cells were first described by Haberlandt (1880) as a morphological modification of palisade cells and seem to be more common in plants of forest understory, probably increasing photosynthetic capacity (Chatelet et al. 2013). In the midrib region, the lacunae of the aerenchyma were larger and wider in E. lagopaivae than in E. blumenavia (Figure 5I–J).

A protrusion on the abaxial leaf surface opposite the central vascular bundle was evidenced in both species (Figure 5I–J, arrows) and the parenchyma cells in this region were regular and rounded. However, adaxial surface of the leaf in E. lagopaivae was flat (Figure 5I), while in E. blumenavia it was possible to observe two protrusions opposite to the vascular bundles adjacent to the midrib (Figure 5J, arrowheads). The alternation of aerenchyma with vascular bundles found in Eithea species was described for other species of the family (Arroyo and Cutler 1984, Meerow 1989, Raymúndez et al. 2000, Alves-Araújo et al. 2012). In Eithea, lacunae of aerenchyma in the pseudopetiole and leaf blade may have been originated by lysis, as suggested for Griffinia, Habranthus, Hippeastrum and Nothoscordum Kunth (Alves-Araújo et al. 2012); however leaf development studies are needed to confirm this hypotheses.

Figure 1. 

Eithea lagopaivae A Habit in flower B Detail of leaf venation C Spathe bracts D Flower with perigone removed, showing stamens and style E Sepals and petals F Tips of sepals and petals F1 Upper sepal F2 Lateral petal F3 Lateral sepal F4 Lower petal G Detail of fimbriae of the paraperigone H Stigma I Longitudinal section of the ovary J Cross section of the ovary K Habit in fruit L Fruit M Seed.

Figure 2. 

Eithea lagopaivae A Typical habitat (October 2016) B Individual plant flowering amid trash dumped at type locality C Flowering plant (Campos-Rocha 1647) D Flower buds E Flower, frontal view (Bernacci 4483) F Flower buds and flowers (Campos-Rocha 1654) G Plants in fruit H Mature capsule exposing the seeds I Seed (elaiosome indicated by the arrow).

Figure 3. 

Eithea blumenavia A Flowering plants in habitat B Lateral view of inflorescence C Detail of spathe bracts D Bracteoles (white arrow) E Sepals and petals (adaxial view) separated from stamens and style. B–E of Campos-Rocha 1624, UEC.

Figure 4. 

Distribution map showing collections of Eithea lagopaivae (red circles) and E. blumenavia (black diamonds). PR = Paraná. SC = Santa Catarina. SP = São Paulo.

Table 1.

Ecological, morphological and anatomic character states that distinguish Eithea lagopaivae from E. blumenavia. CS = cross section.

Character state Eithea lagopaivae Eithea blumenavia
Habitat Semideciduous and deciduous forest Rain forest
Foliage Deciduous Perennial, rarely deciduous
Scape Fully hollow Solid in lower fifth
Spathe bracts Fused more than 1/5th basally Free to fused for up to 1/5th basally
Bracteoles Absent Present
No. flowers per inflorescence 1 2–6, rarely 1
Perigone color White, sometimes with a few magenta striations White with many conspicuous, magenta striations
Width ratio of lateral to lower petals 4:4 to 4:3 4:3 to 4:2
Pseudopetiole margins Laminar Angular
Adaxial epiderm cells (leaf blade) in CS Elongated rectangular Polyhedral
Ornamentation of external periclinal epidermal cell wall (leaf blade) Absent Present
Adaxial surface in the midrib region (leaf blade) in CS Flat 2 protrusions
Figure 5. 

Comparative leaf anatomy of Eithea lagopaivae and E. blumenavia. A Cross section of the pseudopetiole of E. lagopaivae and B E. blumenavia C Cross section detail of the adaxial epidermis of E. lagopaivae and D E. blumenavia E Cross section of the leaf blade of E. lagopaivae and F E. blumenavia G Longitudinal paradermic section detail of the leaf blade, showing the arm-cells of the chlorenchyma in E. lagopaivae and H E. blumenavia (slide of stained fresh material) I Cross section of the leaf blade in the midrib region of E. lagopaivae and J E. blumenavia. * = arm-cell; ab = abaxial epidermis; ad = adaxial epidermis; ae = aerenchyma; ep = epidermis; vb = vascular bundle. Scales bars: 500 µm (A, B); 10 µm (C, D), 50 µm (E, F), 20 µm (G, H); 200 µm (I, J).

Key to the species of Eithea

1 Inflorescence one flowered; bracts fused for more than the lower 1/5th; scape completely hollow; flowers white or only with a few narrow magenta striations; ratio between the width of the lateral and lower petals 4:3 to 4:4; plants from deciduous and semideciduous forest E. lagopaivae
Inflorescence with 2–6 flowers, very rarely 1; bracts free or fused up to the lower 1/5th; scape solid towards the base; flowers with many conspicuous magenta striations; ratio between the width of the lateral and lower petals 4:2 to 4:3; plants from rainforest E. blumenavia


We would like to thank José Roberto Martellini, Luís Carlos Bernacci, and Ricardo Monteiro Goffi for their support in finding the species in the field; Maria do Carmo E. Amaral, and Mauro Peixoto for the access to material of E. blumenavia in cultivation, and MP for the use of a photo of the species in the field (Figure 3A); Klei Sousa for the illustration of E. lagopaivae; Danilo Poso Volet, and Gilberto Bellozi for their assistance with the figures. Renata Souza de Oliveira and anonymous for the careful review. ACR and EFML are grateful to the Programa de Pós-Graduação em Biologia Vegetal/IB-UNICAMP, CAPES and CNPq for the scholarships.


  • Alves-Araújo A, Pessoa E, Alves M (2012) Caracterização morfoanatômica de espécies de Amaryllidaceaes.s. e Alliaceaes.s. do Nordeste brasileiro. Revista Caatinga 25(4): 68–81.
  • Arroyo SC, Cutler DF (1984) Evolutionary and taxonomic aspects of the internal morphology in Amaryllidaceae from South America and southern Africa. Kew Bulletin 39(3): 467–498.
  • Bachman S, Moat J, Hill AW, Torre J, Scott B (2011) Supporting Red List threat assessments with GeoCAT: geospatial conservation assessment tool. ZooKeys 150: 117–126.
  • Carrière E-A (1867) Griffinia blumenavia. Revue Horticole 39: 32–33.
  • Chatelet DS, Clement WL, Sack L, Donoghue MJ, Edwards EJ (2013) The evolution of photosynthetic anatomy in Viburnum (Adoxaceae). International Journal of Plant Sciences 174(9): 1277–1291.
  • Dutilh JHA (1989) Morphological variation in a population of Hippeastrum Herb. Herbertia 45: 152–155.
  • Dutilh JHA (2010) Amaryllidaceae. In: Forzza RC, Baumgratz JFA, Bicudo CEM, Carvalho AA, Costa A, Costa DP, Hopkins M, Leitman PM, Lohmann LG, Maia LC, Martinelli G, Menezes M, Morim MP, Coelho MAN, Peixoto AL, Pirani JR, Prado J, Queiroz LP, Souza VC, Stehmann JR, Sylvestre LS, Walter BMT, Zappi D (Eds) Catálogo das plantas e fungos do Brasil, volume 1.Andrea Jakobsson Estúdio, Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Rio de Janeiro, 842–847.
  • Ficker T (1951) Chromosomes of two narrow-leaved Amaryllis species, and the generic type species of Amaryllis belladonna L. Plant Life 7: 68–71.
  • Flory WS (1977) Overview of chromosomal evolution in the Amaryllidaceae. Nucleus 20: 70–88.
  • García N, Folk RA, Meerow AW, Chamala S, Gitzendanner MA, Oliveira RS, Soltis DE, Soltis PS (2017) Deep reticulation and incomplete lineage sorting obscure the diploid phylogeny of rain-lilies and allies (Amaryllidaceae tribe Hippeastreae). Molecular Phylogenetics and Evolution 111: 231–247.
  • García N, Meerow AW, Soltis DE, Soltis PS (2014) Testing deep reticulate evolution in Amaryllidaceae tribe Hippeastreae (Asparagales) with ITS and Chloroplast sequence data. Systematic Botany 39(1): 75–89.
  • Goldblatt P (1984) (748) Proposal to conserve 1176 Amaryllis and typification of A. belladonna (Amaryllidaceae). Taxon 33(3): 511–516.
  • Haberlandt G (1880) Über eine eigenthümliche Modification des Pallisadengewebes. Vorläufige Mittheilung. Oesterreichische botanische Zeitschrift 30: 305.
  • Ising G (1990) Unexpected effects of a B chromosome in Hippeastrum. Hereditas 112: 4–5.
  • Ising G, Wide-Andersson K (1991) Hippeastrum pardinum crossed to a white H. hybridum. I. Segregation of the B chromosome. Herbertia 47: 11–32.
  • Jones RN, Rees H (1982) B chromosomes. Academic Press, London, 1–266.
  • Karnovsky MJ (1965) A formaldehyde-glutaraldehyde fixative of high osmolality for use in electron microscopy. Journal of Cellular Biology, 27: 137–138.
  • Meerow AW (1989) Systematics of the Amazon lilies, Eucharis and Caliphruria (Amaryllidaceae). Annals of the Missouri Botanical Garden 76(1): 136–220.
  • Meerow AW, Guy CL, Li Q-B, Yang S-L (2000) Phylogeny of the American Amaryllidaceae based on nrDNA ITS sequences. Systematic Botany 25(4): 708–726.
  • Naranjo CA (1969) Cariotipos de nueve espécies argentinas de Rhodophiala, Hippeastrum, Zephyranthes y Habranthus (Amaryllidaceae). Kurtziana 5: 67–87.
  • Naranjo CA, Andrada AB (1975) El cariotipo fundamental en el genéro Hippeastrum Herb. (Amaryllidaceae). Darwinia 19: 566–582.
  • Oliveira JB, Prado H (1989) Carta pedológica semidetalhada do Estado de São Paulo: folha de Piracicaba. Instituto Agronômico de Campinas, Campinas.
  • Oliveira RS (2012) O gênero Hippeastrum Herb. (Amaryllidaceae) no Brasil: evidências de evolução reticulada e análise de caracteres florais. PhD Thesis, Universidade Estadual de Campinas, Brazil.
  • Radford AE, Dickison WC, Massey JR, Bell CR (1974) Vascular Plant Systematics. Harper & Row Publishers, New York, 891 pp.
  • Ravenna P (2002) Eithea, a new genus of Brazilian Amaryllidaceae. Botanica Australis 1: 1–8.
  • Raymúndez MB, Xena de Enrech N, Escala M (2000) Estudios morfoanatómicos foliares en especies del género Hymenocallis Salisb. (Amaryllidaceae) presentes en Venezuela: relación entre los caracteres morfoanatómicos foliares y el ambiente en el que se desarrollan las plantas. Acta Botanica Venezuelica 23(1): 69–87.
  • Satô D (1938) Karyotype alteration and phylogeny. IV. Karyotypes in Amaryllidaceae with special reference to the SAT-chromosome. Cytologia 9: 203–242.
  • Satô D (1942) Karyotype alteration and phylogeny in Liliaceae and allied families. Japanese Journal of Botany 12: 57–161.
  • Sealy JR (1937) Hippeastrum blumenavia (C. Koch et Bouché ex Carr.) Sealy. Curtis’s Botanical Magazine 160: t. 9504.
  • Stearn WT (2004) Botanical Latin. Timber Press, Portland, 560 pp.
  • Thiers B (2017) Index Herbariorum: a global directory of public herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. [continuously updated; accessed 15.3.2017]
  • Traub HP (1938) Subgenus Sealyana, genus Amaryllis (Linn. ex Parte) Uphof, Amaryllidaceae. Herbertia 5: 131.
  • Traub HP (1983) Griffinia, not Amaryllis — Corrections. Plant Life 39: 16.