Monograph |
Corresponding author: Paul M. Peterson ( peterson@si.edu ) Academic editor: Clifford Morden
© 2016 Paul M. Peterson, Robert J. Soreng.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Peterson PM, Soreng RJ (2016) A revision of Poa subsection Aphanelytrum (Poaceae, Pooideae, Poaeae, Poinae); and a new species, Poa auriculata. PhytoKeys 63: 107-125. https://doi.org/10.3897/phytokeys.63.8198
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In this study the peculiar Andean grass genus Aphanelytrum, with two species, is reduced to Poa subsect. Aphanelytrumcomb. & stat. nov. A third species, Festuca reclinata, is assigned to the subsection, which shows states transitional between a more typical Poa and Aphanelytrum. Poa subgen. Poa supersect. Homalopoa sect. Dioicopoa subsect. Aphanelytrumcomb. & stat. nov. is characterized in having stooling perennials with decumbent to spreading culm bases that continuously branch and often root at low to mid-culm nodes, glabrous spikelets with long rachillas 1.2–4.2 mm long, short glumes less than ½ the length of the florets, and lemmas with bifid apexes that are mucronate to short-awned. We provide for the three species taxonomic discussions, morphological and anatomical descriptions, keys, illustrations, and a list of specimens. Also, we provide two new names, Poa hitchcockiana nom. nov. and Poa sanchez-vegae nom. nov., and one new combination, Poa reclinata comb. nov. A new species, Poa auriculata sp. nov. from Peru, not thought to be a member of P. subsect. Aphanelytrum, is presented. It is the first in the genus with prominent auricles. In addition, we place Poa apiculata in Poa subgen. Poa supersect. Homalopoa sect. Dioicopoa subsect. Tovarochloacomb. & stat. nov.
En este estudio el género peculiar de gramíneas andinas Aphanelytrum, representado por dos especias, ha sido reducido a Poa subsecc. Aphanelytrumcomb. & stat. nov. Una tercera especie es incluida en la subsección, Festuca reclinata, esta presenta características transicionales entre las especies más típicas de Poa y Aphanelytrum. Poa subgen. Poa supersecc. Homalopoa secc. Dioicopoa subsecc. Aphanelytrumcomb. & stat. nov. se caracteriza por incluir plantas perennes, stoloniferas, con los culmos decumbentes o extensos, continuamente ramificados, a menudo enraizados en los nudos basales hasta los intermedios, las espiguillas son glabras con rachillas largas de 1.2–4.2 mm de longitud, las glumas más cortas son de la ½ de longitud de los flósculos y las lemas con los ápices bífidos son mucronadas hasta breve-aristadas. Nosotros proveemos para las tres especias discusiones taxonómicas, descripciones morfológicas y anatómicas, claves, ilustraciones y la lista de las muestras usadas. Tambien, proveemos dos nombres nuevos - Poa hitchcockiana nom. nov. y Poa sanchez-vegae nom. nov., y una combinación -Poa reclinata comb. nov. Una nueva especie - Poa auriculata sp. nov. de Perú es presentada. Esta es la especie primera del género con prominentes aurículas. En adición, transferimos Poa apiculata a Poa subgen. Poa supersecc. Homalopoa secc. Dioicopoa subsecc. Tovarochloacomb. & stat. nov.
Anatomy, Aphanelytrum , descriptions, Dioicopoa , Homalopoa , illustrations, key, morphology, taxonomy, Tovarochloa
The genus Aphanelytrum (Hack.) Hack., first named without a description by
Aphanelytrum procumbens is a peculiar grass for having spikelets with minute and unveined glumes and two or three florets that are widely-spaced because of the long flexuous rachillas that are ½ to ¾ as long as the florets, the lemmas are keeled and 5-veined (
The placement and evolutionary relationships of Aphanelytrum have been controversial since its inception. It was originally placed in the subfamily “Festuceae” [Festucoideae], applied in the broad sense of
Based on ITS sequences,
Festuca reclinata Swallen, known only from the Páramo del Almorzadero in the Cordillera Oriental of Colombia, has been linked to Aphanelytrum based on exhibiting similar morphologies (
The main goal of this study is to present a systematic revision Poa subsect. Aphanelytrum comb. & stat. nov. that includes three species. We make a new combination for F. reclinata, and provide new names for Aphanelytrum procumbens and A. peruvianum. In addition, we include a key to the species, complete descriptions, illustrations, distribution, specimens examined, and comments for these three species. Furthermore, we place Poa apiculata in Poa subsect. Tovarochloa comb. & stat. nov.
While reviewing Peruvian specimens of Poa, Robert J. Soreng (RJS) found a peculiar collection by John J. Wurdack (Wurdack 1145) from Departamento Amazonas, Provincia Chachapoyas located on the summit of Puma-urcu that is similar to Poa scabrivaginata Tovar and Festuca reclinata but differed from the forgoing, and all other Poa species, in having auriculate collars. We describe this as a new species of Poa, but do not include it as a member of P. subsect. Aphanelytrum.
Herbarium specimens from the following 13 herbaria were examined:
For leaf anatomy, 5 mm long leaf blades were taken from dried herbarium specimens, rehydrated in boiling water, and fixed in FAA for 24 hours. They were transferred to 70% ethanol, followed by a water rinse and treated for three hours in 50% hydrofluoric acid (
within Poa subg. Poa supersect. Homalopoa sect. Dioicopoa E. Desv., see
Brachyelytrum subg. Aphanelytrum Hack., Die Nat. Pflanzenfam., Nachträge zu Teil II, Abteilung 2. 42. 1897.
Aphanelytrum (Hack.) Hack., Oesterr. Bot. Z. 52: 12. 1902. Aphanelytrum procumbens (Hack.) Hack., Oesterr. Bot. Z. 52: 13, text f. 1902.
Aphanelytrum Hack. ex Sodiro, Anales Univ. Centr. Ecuador 3(25): 480. 1889, nom. nud.
Based on Brachyelytrum procumbens Hack. ≡ Aphanelytrum procumbens (Hack.) Hack. ≡ Poa hitchcockiana.
Poa subsect. Aphanelytrum differs from most species of Poa in having stooling perennials with decumbent to spreading culm bases that continuously branch and often root at low to mid-culm nodes, glabrous spikelets with long rachillas 1.2–4.2 mm long, short glumes less than ½ the length of the florets, and lemmas with bifid apices that are mucronate to short-awned.
Stooling perennials with intravaginal innovations. Culms 14–80 (–100) cm tall, decumbent to spreading near base, culm bases that continuously branch and often root at low to mid-culm nodes. Leaf blades 3–14 cm long, 0.2–5 (–5.5) mm wide, flat to loosely involute; ligules 1–3 mm long, membranous. Panicles few-flowered with 5–22 spikelets. Spikelets 5–18 mm long, 2–4-flowered, membranous, glabrous, disarticulating above the glumes and between the florets; rachilla 1.2–4.2 mm long, terete in cross section, often prolonged above upper floret; callus glabrous; glumes 0.1–3.5 mm long, less than ½ the length of the florets, 0–3 (–4)-veined; lemmas 2.2–9.6 mm long, 3- or 5-veined, lanceolate or ovate, apex bifid, mucronate to short-awned, if awned up to 2 mm long; paleas 2–7 mm long, apex bifid; lodicules 2, glabrous; stamens 3, anthers 2–4.7 mm long; ovaries glabrous. Caryopses compressed laterally or unknown.
Three species of northern to central Andes of South America.
1 | Glumes veinless, 0.1−0.5 (–0.7) mm long, minute or absent | Poa hitchcockiana |
– | Glumes veined, 1−3.6 mm long, lower glumes 1 or 3-veined, upper glumes 3 or 4-veined | 2 |
2 | Spikelets 10–13 cm long, 4-flowered; lemmas 6.6–8 mm long; leaf blades 3–5 mm wide; paleas 4.6–5.2 mm long; culm internodes 14–80 mm long | Poa reclinata |
– | Spikelets 5–7 mm long, 3-flowered; lemmas 2.2–3.5 mm long; leaf blades 0.2–1.2 mm wide; paleas 2–3.2 mm long; culm internodes 3−18 mm long | Poa sanchez-vegae |
Brachyelytrum procumbens Hack., Die Nat. Pflanzenfam., Nachträge zu Teil II, Abteilung 2. 42. 1897. Aphanelytrum procumbens (Hack.) Hack., Oesterr. Bot. Z. 52: 13, text f. 1902.
Aphanelytrum decumbens Hack. ex Sodiro, Anales Univ. Centr. Ecuador 3(25): 480. 1889, nom. nud.
ECUADOR. Crescit in silvis opacis regionis subandinis, 2000 m, Jul 1887, L. Sodiro, s.n. (holotype: W-19813 seen digitally!; isotype:
Straggling and stooling perennials with intravaginal innovations. Culms 30–80 (–100) cm tall, decumbent to erect, delicate, glabrous; nodes 3–8 (–14); internodes 2–14 cm long. Leaf sheaths ½ to 4/5 as long as the internodes, membranous to hyaline, often shiny, upper sheaths open ½ the length, keeled; ligules 1–2 mm long, membranous to hyaline, apex erose, often lacerate; blades 6–14 cm long (flag leaf usually 4–6 cm long), 1.5–4.2 (–5.5) mm wide, flat, thin, lax, linear. Panicles 5–18 (–22) cm long, 2–5 cm wide, few-flowered with 10–22 spikelets, oblong; branches flexuous, effuse and spreading, the lower branches capillary with 2–5 spikelets immediately branching below, the upper branches usually with 2 spikelets. Spikelets 8–18 mm long, 2- or 3-flowered (often appearing 1-flowered with disarticulation of upper florets), laterally compressed, greenish; disarticulation between the florets; all florets usually perfect; rachilla joints 1.5–4.2 mm long, often prolonged above upper floret; glumes 0.1–0.5 (–0.7) mm long, without veins, minute or absent, apex acute or irregularly lobed or toothed; lemmas 5–9.6 mm long, 5-veined, lanceolate, apex acuminate, mucronate or short-awned, the awn up to 2 mm long; paleas 4–7 mm long, 2-keeled, apex bifid; lodicules 0.8–1.1 mm long, lanceolate, membranous, glabrous; stamens 3; anthers 2.8–4.7 mm long, yellowish; ovaries glabrous with two styles and two stigmas. Caryopses 3.25–4.2 mm long, compressed laterally, glabrous, hilum short.
The transverse section leaf anatomy of Poa hitchcockiana is C3, XyMS+ with non-radiate, spongy chlorenchyma, without adaxial palisade cells. There is a single primary vascular bundle associated with the midrib and a sclerenchyma girder 2 or 3-cells thick on the abaxial surface (Fig.
Poa hitchcockiana: A Habit B Panicle C Sheath, ligule, and blade D Spikelet E Lower floret with glumes at base F Glumes at base of lower floret G Lemma H Palea, ventral view I Stamens with ovary J Lodicules at base of ovary K Pistil, lodicules at base L Caryopsis M cross section of caryopsis. A–D, J–K (Peterson 16571 & Refulio Rodriguez) E, F, L, M (Apollinaire 717 & Arthur,
Leaf blade transverse sections of Poa sanchez-vegae (A–C) and Poa hitchcockiana (D). Poa sanchez-vegae: A Entire leaf blade B Midvein showing a single primary vascular bundle with bulliform cells (b indicated by arrows) C Lateral primary vascular bundle with a few associated abaxial sclerenchyma fibers (sf) and spongy chlorenchyma (chl). Poa hitchcockiana: D Midvein showing a single primary vascular bundle with abaxial sclerenchyma fibers (sf) and collapsed chlorenchyma.
Flowering year round [?], although no collections made in February, May, and September.
Poa hitchcockiana is found along the paramo or moist jalca vegetation between 2000–4025 m of the Cordillera de los Andes in Colombia, Ecuador, Bolivia, and Peru.
Since the species is widespread it is of least concern (
Since the epithets procumbens and decumbens are blocked in Poa by the earlier P. procumbens Curtis and P. decumbens (L.) Scop., we provide a new name commemorating the “father of American agrostology,” Albert Spear Hitchcock (1865–1935).
The only wide ranging species of Poa subsect. Aphanelytrum, P. hitchcockiana also has the most unusual spikelet morphology with extremely long rachillas (1.5–4.2 mm long) and very short [0.1–0.5 (–0.7) mm long] to obscure or often absent, unveined glumes. Poa rachillas rarely exceed 1.5 mm, but some have spikelets with rachillas up to 2 mm long (e.g. P. sect. Secundae V.L. Marsh ex Soreng) P. curtifolia Scribn., P. hartzii Gand., P. stenantha Trin.; (P. sect. CenisiaeAsch. & Graebn.) P. davisii Bor; (P. supersect. Homalopoa) P. bajaensis Soreng, and a few other species in the Homalopoa (H) clade (see
Bolivia. El Beni: Bella Vista, 26 Dec 1923, A.S. Hitchcock 22756 (
Festuca reclinata Swallen, Contr. U.S. Natl. Herb. 26(6): 254. 1949.
COLOMBIA. Departamento Santander, Cordillera Oriental, Paramo de Almorzadero, 3500–3700 m, 20 Jun 1940, J. Cuatrecasas & H. Garcia Barriga 9970 (holotype:
Stooling perennials forming small tussocks with intravaginal innovations. Culms 30–40 cm tall, decumbent to erect, often weak, spreading to prostrate, culm bases continuously branch and often root at low to mid-culm nodes, glabrous; nodes 2 or 3 in distal half; internodes 1.4–8.0 cm long. Leaf sheaths about 2/3 as long as the internodes, membranous, greenish-white, scabrous, upper sheaths open 1/2 the length, collars flared; ligules 1–2.5 mm long, membranous, apex acute, ephemeral; blades 5–15 cm × 0.3–0.5 mm, flat, thin, lax, green, abaxially scabrous. Panicles 9–10 × 2–3 cm, few-flowered with 5–8 spikelets, flexuous, ovate, branched; branches glabrous. Spikelets 10–13 mm long, 4-flowered, glabrous; obovate; rachilla 1.2–2.4 mm long, minutely scabrous; glumes 1.3–3.6 mm long, membranous, lanceolate, green, glabrous, upper margins hairy; lower glumes 1.3–2 mm long, 1-nerved, apex acute; upper glumes 3–3.5 mm long, less than ½ as long as the florets, 3-veined, apex acuminate; lemmas 6.6–8 mm long, 5-veined, lanceolate, membranous, green, scabrous, apex bifid, two-dentate, awned between the teeth, the awn 1–2 mm long; paleas 4.6–5.2 mm long, membranous, keels scabrous, apex bifid; lodicules 0.6–0.8 mm long, lanceolate; anthers 2.7–3.3 mm long; ovaries glabrous. Caryopses not seen.
The leaf anatomy of Poa reclinata is C3, XyMS+ and the transverse sections have many widely spaced vascular bundles with small ribs; sclerenchyma is under both abaxial and adaxial epidermis, discontinuous, small, extending to the vascular bundles forming girders; bulliform cells are absent; epidermis is sparsely hairy. An anatomical description of P. reclinata is also found in
Flowering in July.
Poa reclinata is known only from the type locality, the paramo of the Colombian Cordillera Oriental, Dept. Santander (
The species is rare and its conservation status is data deficient (
The specific epithet is probably in reference to the decumbent, spreading or prostrate culms, a frequent characteristic of the species in this subsection of Poa.
Aphanelytrum peruvianum Sánchez Vega, P.M. Peterson, Soreng & Lægaard, J. Bot. Res. Inst. Texas 1(2): 842. 2007.
PERU. Departamento Cajamarca, Provincia Cajamarca, Distrito Cajamarca, Cerro Akumullca, al SO de Cajamarca, sobre la cima de la ladera occidental del Valle de Cajamarca (7°14'15"S Lat, 78°29'24"W Long), 3300 m, 20 Mar 2003, I. Sánchez-Vega 11781, M. Sánchez-Montoya, R. Cueva R. & J. Montoya (holotype:
Caespitose perennials. Culms 14−24 cm tall, with many culms near base, primary and secondary culms appressed, somewhat decumbent near base with intravaginal branching, culm bases continuously branch and often root at low to mid-culm nodes; internodes 3−18 mm long, numerous. Leaf sheaths longer than the internodes, membranous to hyaline, open to near base to open completely to base, slightly keeled; ligules 2−3 mm long, membranous to hyaline, decurrent, apex erose often lacerate; blades 3−7 cm long (flag leaf ca 1.6 mm long), 0.2−1.2 mm wide, flat to loosely involute, thin, linear, apex naviculate. Panicles 1.7−2.5 cm long, few-flowered with 5−10 spikelets; branches flexuous, the lower branches with two spikelets, the upper branches with single spikelet. Spikelets 5−7 mm long, usually 3-flowered, purplish, glabrous, disarticulating above the glumes and between the florets; lower and middle florets usually staminate; upper florets usually pistillate; rachilla joints 1.2−2 mm long, prolonged above the upper floret; glumes 1−2 mm long, subequal, apex acute, often mucronate; lower glume linear, 1-veined; upper glume oblanceolate, 3(4-)-veined, often toothed or irregularly lobed minutely bifid; lemmas 2.2−3.5 mm long, 3- or 5-veined, ovate, apex mucronate with two acute lobes on each side of the mucro, the mucro 0.1−0.3 mm long; paleas 2−3.2 mm long, 2-keeled, apex bifid; lodicules 0.7−0.8 mm long, lanceolate, membranous, glabrous; stamens 3; anthers 2−2.9 mm long, yellowish to purplish; ovaries glabrous with two styles and two stigmas. Caryopses glabrous.
The transverse section leaf anatomy of Poa sanchez-vegae is C3, XyMS+ with non-radiate, spongy chlorenchyma, without adaxial palisade cells (Fig.
Flowering in March.
Poa sánchez-vegae is known only from the type locality near the western highlands of the Cajamarca Valley and is found on rocky sites associated with jalca vegetation (humid alpine grass ecosystems) at 3300 m (
Poa sanchez-vegae is rare and the conservation status is data deficient (
Since the existing specific epithet was occupied in Poa we provide a new name commemorating Isidoro Sánchez Vega, a renowned Peruvian Botanist.
Based on morphological characters, Isidoro Sánchez-Vega in consultation with Simon Lægaard, first identified the type collection of P. sanchesz-vegae as an unknown species of Aphanelytrum. In
Poa sanchez-vegae (A, B, D–L) and Poa hitchcockiana (C). Poa sanchez-vegae: A Habit B Sheath, ligule, and blade D Panicle E Spikelet F Glumes, showing lower 1-veined and upper 4-veined G Glumes, showing lower 1-veined and upper 3-veined H Lemma I Paleas J Palea, anthers, and rachilla K Lodicules and pistil L Pistil. (Sánchez Vega 11781, Sánchez Montoya, Cueva R. & Montoya,
within Poa subg. Poa supersect. Homalopoa sect. Dioicopoa E. Desv., see
Tovarochloa T.D. Macfarl. & P. But, Brittonia 34(4): 478. 1982.
Based on Tovarochloa peruviana T.D. Macfarl. & P. But ≡ Poa apiculata Refulio.
For consistency in rank, since Poa apiculata Refulio (≡ Tovarochloa peruviana) apparently is sister to the three species in Poa subsect. Aphanelytrum, we erect Poa subsect. Tovarochloa.
PERÚ. Departamento Amazonas, Provincia Chachapoyas, summit of Puma-urcu southeast of Chachapoyas, occasional on dry cliff face, 3100–3200 m, 3 Jul 1962, J.J. Wurdack 1145 (holotype:
Poa auriculata differs from Poa scabrivaginata Tovar in having 4–6-flowered spikelets, a glabrous callus, glumes 2–3 mm long, and lemmas 2.5–3.8 mm long.
Caespitose, annuals or short-lived perennials. Culms 40–72 cm tall, erect, scabrous, shiny, often weak; nodes 3–5. Leaf sheaths 2/3 to 4/5 as long the internodes, membranous, greenish to stramineous, scabrous, upper sheaths open for 1/3 the length, keeled, summit with prominent triangular auricles; ligules 3.3–5 mm long, membranous to hyaline, apex erose, often split down the center; blades 6–15 cm long (flag leaf 3–6 cm long), 3–6 mm wide, flat, thin, lax, linear, scabrous. Panicles 5–11 cm long, 2.5–5 cm wide, ovate, open; branches flexuous, effuse and spreading with numerous spikelets, scabrous, the lower branches capillary. Spikelets 5–7 mm long, 4–6-flowered, glabrous, ovate, greenish-yellow tinged with purple; rachilla 0.4–1.0 mm long; glumes 2–3 mm long, membranous, subequal; lower glumes 2–2.5 mm long, 1-veined, linear lanceolate, apex acuminate; upper glumes 2.4–3 mm long, 3-veined, the veins not conspicuous, lanceolate, apex acute; lemmas 2.5–3.8 mm long, 5-veined, lanceolate, membranous; apex acute, unawned; paleas 2.3–3.7 mm long, membranous, 2-keeled, the keels scabrous, apex minutely bifid; lodicules 0.4–0.5 mm long, ovate, membranous, glabrous; stamens 3; anthers 1.9–2.1 mm long, yellowish; ovaries glabrous with two styles and two stigmas. Caryopses not seen.
Flowering in June and July.
Poa auriculata is known only from the type locality in Cordillera de los Andes of Peru near Chachapoyas between 3100–3200 m growing on a dry cliff face.
The species is rare, but its conservation status is data deficient (
The specific epithet refers to the triangular auricles that are found on the summit of the sheaths, a feature that is unique among species of Poa.
Initially RJS considered Poa auriculata to be related to species in P. subsect. Aphanelytrum. We do not place the new species in P. subsect. Aphanelytrum because the spikelets have short rachillas and are 4–6-flowered, the habit is annual to short-lived perennials with erect culms, and the lemmas are unawned without mucros. However, aside from the auricles, P. auriculata is morphologically consistent with the 300 or so species that reside within P. subg. Poa supersect. Homalopoa. We hope to include a sample of this species in upcoming molecular analyses.
Poa scabrivaginata differs from P. auriculata in having 2-flowered spikelets (4–6 in P. auriculata), a few cobwebby hairs on the callus (verses glabrous), glumes 3.6–4.3 mm long (verses 2–3 mm), and lemmas 4.2–4.5 mm long (verses 2.5–3.8 mm) [
We thank the Smithsonian Institution’s Restricted Endowment Fund, the Scholarly Studies Program, Research Opportunities, Atherton Seidell Foundation, Biodiversity Surveys and Inventories Program, Small Grants; the National Geographic Society for Research and Exploration (Grant No. 8087-06); Alice R. Tangerini for preparing the illustrations and anatomical plate; Stan Yankowski for preparing the anatomical sections; two anonymous reviewers and Clifford Morden for suggesting improvements to the manuscript.