GrassBase - The Online World Grass Flora

Descriptions

W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Poa

HABIT Annual (25), or perennial (476). Rhizomes absent (365), or short (49), or elongated (94). Stolons absent (468), or present (36). Culms erect (240/324), or geniculately ascending (120/324), or decumbent (39/324), or prostrate (3/324), or rambling (5/324); robust (14/46), or slender (24/46), or weak (8/46); 1–38.93–400 cm long; firm (488), or wiry (8); without nodal roots (4/18), or rooting from lower nodes (18/18). Culm-internodes similar in length (1/2), or unequal, the upper longer (1/2); terete (158/183), or elliptical in section (31/183). Culm-nodes flush with internodes (1/4), or swollen (3/4). Lateral branches lacking (333/343), or sparse (10/343), or ample (8/343). Culm-sheaths persistent (1/1). Leaf-sheaths open for most of their length (40/80), or tubular for much of their length (40/80). Leaf-sheath auricles absent (495), or erect (1). Ligule an eciliate membrane (457), or a ciliolate membrane (42), or absent (1). Leaf-blades persistent (487), or deciduous at the ligule (9); aciculate (9), or filiform (54), or linear (436), or oblong (1), or triangular (1); herbaceous (470), or coriaceous (28); stiff (65), or firm (399), or flaccid (34); without exudate (495), or pruinose (2). Leaf-blade midrib evident (1/3), or conspicuous (2/3). Leaf-blade venation without cross veins (495), or with obscure cross veins (1). Leaf-blade margins unthickened (3/10), or cartilaginous (7/10). Leaf-blade apex muticous (480), or pungent (16).

INFLORESCENCE Bisexual (442), or gynodioecious ("male", in this context, indicating the bisexual state) (10), or monoecious (1), or dioecious (46); with male and female spikelets in the same inflorescence (1/56), or with male and female spikelets in different inflorescences (55/56), or with sex changing according to season (1/56). Inflorescence a panicle (494), or comprising only a few spikelets (3); subtended by an unspecialized leaf-sheath (495), or bracts (1); exserted (485), or embraced at base by subtending leaf (14), or enclosed (1). Peduncle tipped by a glumaceous appendage (1/1).

Panicle open (375/493), or contracted (122/493), or spiciform (21/493). Primary panicle branches not whorled (482/494), or whorled at lower nodes (3/494), or whorled at most nodes (9/494).

Spikelets appressed (2/6), or ascending (2/6), or spreading (1/6), or pendulous (1/6); solitary (495), or in pairs (1). Fertile spikelets sessile (1), or sessile and pedicelled (1), or pedicelled (495). Male spikelets pedicelled (1/1); 1 in a cluster (1/1). Pedicels filiform (1/3), or oblong (1/3), or clavate (1/3); tip rectangular (1/2), or widened (1/2).

FERTILE SPIKELETS Spikelets comprising 1–4–13 fertile florets; without rhachilla extension (3/495), or with a barren rhachilla extension (117/495), or with diminished florets at the apex (376/495). Spikelets linear (1/495), or lanceolate (31/495), or elliptic (52/495), or oblong (286/495), or ovate (195/495), or orbicular (2/495), or obovate (5/495), or oblanceolate (1/495), or cuneate (15/495); laterally compressed; 1.5–5.383–15 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes definite (488/488); glabrous (455/488), or sparsely hairy (20/488), or pubescent (25/488), or pilose (5/488), or villous (1/488). Floret callus glabrous (238/478), or sparsely hairy (17/478), or pubescent (15/478), or pilose (19/478), or bearded (4/478), or woolly (235/478).

GLUMES Glumes persistent; shorter than spikelet (491), or reaching apex of florets (6), or exceeding apex of florets (3); thinner than fertile lemma (2), or similar to fertile lemma in texture (495); incurved at apex (2), or parallel to lemmas (491), or recurved at apex (1), or gaping (3). Lower glume linear (12/495), or lanceolate (299/495), or elliptic (42/495), or oblong (66/495), or ovate (108/495); not clasping (1/1); 0.33–0.8489–1.5 length of upper glume; membranous (487/494), or chartaceous (3/494), or herbaceous (3/494), or coriaceous (1/494); without keels (3/494), or 1-keeled (491/494); 1 -veined (302/456), or 2 -veined (91/456), or 3 -veined (244/456), or 4–5 -veined (4/456). Lower glume lateral veins absent (283), or obscure (60), or distinct (224), or prominent (2); without ribs (285/286), or ribbed (1/286). Lower glume surface smooth (452), or asperulous (35), or scabrous (23); without pits; glabrous (494), or pubescent (1), or pilose (1). Lower glume apex entire (493), or erose (3); emarginate (1/495), or obtuse (29/495), or acute (414/495), or acuminate (76/495), or attenuate (2/495), or setaceously attenuate (1/495); muticous (493/495), or mucronate (3/495). Upper glume linear (3/495), or lanceolate (164/495), or elliptic (83/495), or oblong (71/495), or ovate (214/495), or obovate (5/495); 0.25–0.8626–1.7 length of adjacent fertile lemma; membranous (487/494), or chartaceous (3/494), or herbaceous (3/494), or coriaceous (1/494); with undifferentiated margins (442), or hyaline margins (46), or membranous margins (1), or scarious margins (7); without keels (3/494), or 1-keeled (491/494); 1 -veined (18/471), or 2 -veined (14/471), or 3 -veined (458/471), or 4 -veined (19/471), or 5 -veined (26/471), or 6–7 -veined (1/471). Upper glume primary vein eciliate (495), or ciliolate (1), or ciliate (1). Upper glume lateral veins without ribs (490/491), or ribbed (1/491); meeting at apex (1/1). Upper glume surface smooth (445), or asperulous (43), or scabrous (22), or papillose (2); glabrous (493), or pubescent (2), or pilose (1). Upper glume apex entire (492), or erose (5); emarginate (4/494), or truncate (1/494), or obtuse (49/494), or acute (408/494), or acuminate (62/494), or attenuate (1/494); muticous (493/495), or mucronate (2/495).

FLORETS Fertile florets bisexual (449), or female (55). Fertile lemma linear (2/495), or lanceolate (73/495), or elliptic (55/495), or oblong (110/495), or ovate (283/495), or oblate (1/495); without auricles (495), or auriculate at base (1), or thickened on margins at base (1); laterally compressed (2/2); lanceolate in profile (22/134), or elliptic in profile (9/134), or oblong in profile (112/134), or ovate in profile (1/134); membranous (475/494), or chartaceous (8/494), or herbaceous (6/494), or coriaceous (6/494); of similar consistency above (443), or much thinner above (52), or firmer above (1); of similar consistency on margins (427), or much thinner on margins (69); without keel (1), or keeled (495); wingless; 0–5–11 -veined. Lemma midvein without distinctive roughness (399), or scaberulous (51), or scabrous (62); eciliate (273), or ciliolate (63), or ciliate (148), or pectinately ciliate (1), or pubescent (34). Lemma lateral veins obscure (57/136), or with distinct primaries but obscure intermediates (21/136), or distinct (30/136), or prominent (32/136); extending close to apex (2/36), or stopping well short of apex (32/36), or less than two thirds length of lemma (2/36). Lemma surface smooth (389), or granulose (8), or asperulous (31), or scaberulous (66), or scabrous (40), or papillose (9), or punctate (4), or pitted (1); unwrinkled; without grooves; glabrous (369), or puberulous (51), or pubescent (98), or pilose (16), or hirsute (2), or villous (2); hairy on back (100/162), or on veins (55/162), or between veins (9/162), or in lines (1/162); with simple hairs (161/162), or turgid hairs (1/162); without hair tufts (495), or with basal hair tufts near margin (1). Lemma margins flat (495), or involute (1); eciliate (322), or ciliolate (51), or ciliate (111), or pubescent (25), or pilose (2), or villous (2), or woolly (1). Lemma apex entire (483), or erose (9), or dentate (7); 2 -fid (5/6), or 3 -fid (1/6); incised 0.2 of lemma length; emarginate (6/487), or truncate (6/487), or obtuse (148/487), or acute (343/487), or acuminate (20/487), or cuspidate (2/487), or apiculate (2/487); muticous (486), or mucronate (16), or awned (5); 1 -awned (5/5). Principal lemma awn apical (15/19), or from a sinus (4/19). Palea 0.2–0.9418–1 length of lemma; 2 -veined (8/9), or 3 -veined (1/9). Palea keels separated (494), or approximate (2); wingless (495), or winged (1); smooth (213), or scaberulous (101), or scabrous (196), or spinulose (2); eciliate (391), or puberulous (5), or pubescent (1), or ciliolate (82), or ciliate (33). Palea surface glabrous (452), or puberulous (24), or pubescent (37), or pilose (3). Palea apex entire (1/8), or dentate (8/8). Apical sterile florets resembling fertile though underdeveloped (371/376), or distinct from fertile (5/376).

FLOWER Lodicules 1 (1/444), or 2 (443/444); membranous (442/442); glabrous (442/444), or ciliate (9/444); with a small lateral lobe (2/3), or irregularly toothed (1/3); obtuse (1/1). Anthers 1 (1/489), or 3 (488/489). Stigmas 2–3 (1/1). Ovary glabrous (11/11).

FRUIT Caryopsis with adherent pericarp (461/461); lanceolate (4/49), or fusiform (8/49), or ellipsoid (19/49), or oblong (11/49), or ovoid (5/49), or obovoid (1/49), or oblanceolate (1/49); laterally compressed (1/1); trigonous (15/15); striate (1/2), or rugose (1/2). Embryo 0.2–0.2567–0.33 length of caryopsis. Hilum punctiform (446/448), or elliptic (2/448).

MALE Male inflorescence similar to female (51/51); a panicle (1/1). Male spikelets resembling female (46/51), or similar to female but less developed (4/51), or distinct from female (1/51); lanceolate (1/1). Male spikelet glumes 2 (3/3).

DISTRIBUTION Europe (54), or Africa (29), or Temperate Asia (158), or Tropical Asia (96), or Australasia (84), or Pacific (7), or North America (80), or South America (120), or Antarctica (10).

Please cite this publication as detailed in How to Cite Version: 27th January 2014.