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.

Leymus

HABIT Perennial. Rhizomes absent (17), or short (14), or elongated (29). Culms erect (31/34), or geniculately ascending (8/34), or decumbent (1/34); robust (2/2); 10–71.77–350 cm long. Culm-internodes terete (1/1). Culm-nodes constricted (1/1). Lateral branches sparse (2/3), or fastigiate (1/3). Leaf-sheath auricles absent (50), or falcate (11). Ligule an eciliate membrane (57), or a ciliolate membrane (2). Leaf-blades filiform (1), or linear (58), or lanceolate (2); herbaceous (20), or coriaceous (39); stiff (51), or firm (8). Leaf-blade apex muticous (55), or pungent (4).

INFLORESCENCE Inflorescence composed of racemes; exserted (58), or embraced at base by subtending leaf (1).

Racemes single; erect (19), or ascending (38), or drooping (3); linear (57), or oblong (5); bilateral; bearing 10–18 fertile spikelets on each (1/1). Rhachis flattened (27/27). Spikelet packing broadside to rhachis; crowded (12), or contiguous (34), or lax (12), or distant (1); 2 -rowed (2/2). Rhachis internodes indefinite (29), or filiform (1), or linear (28), or oblong (1). Rhachis internode tip flat (1/1).

Spikelets appressed (19/20), or ascending (1/20); solitary (15), or in pairs (44), or in threes (21), or clustered at each node (6). Fertile spikelets sessile (54), or sessile and pedicelled (4), or pedicelled (3); 1 in the cluster (7/50), or 2 in the cluster (45/50), or 3 in the cluster (23/50), or 4 in the cluster (8/50), or 5 in the cluster (6/50), or 6 in the cluster (3/50), or 7–11 in the cluster (1/50).

FERTILE SPIKELETS Spikelets comprising 1–5–12 fertile florets; with a barren rhachilla extension (5), or with diminished florets at the apex (54). Spikelets lanceolate (7), or elliptic (25), or oblong (29), or cuneate (1); laterally compressed (54), or dorsally compressed (5); 5–14.55–32 mm long; breaking up at maturity; disarticulating below each fertile floret (58), or above glumes but not between florets (1). Spikelet callus glabrous (2/4), or pilose (2/4); base truncate (2/2). Rhachilla internodes definite; glabrous (41), or sparsely hairy (2), or pubescent (14), or pilose (2). Floret callus glabrous (2/9), or sparsely hairy (1/9), or pubescent (4/9), or pilose (3/9).

GLUMES Glumes both absent or obscure (2), or one the lower absent or obscure (1), or two (58); distichous (43), or collateral (16); persistent; shorter than spikelet (51/55), or reaching apex of florets (9/55), or exceeding apex of florets (3/55). Lower glume subulate (28/58), or linear (13/58), or lanceolate (22/58), or oblong (1/58); 0.5–0.9622–1 length of upper glume; chartaceous (2/40), or herbaceous (1/40), or coriaceous (37/40); without keels (2/12), or 1-keeled (10/12); 0 -veined (3/55), or 1 -veined (43/55), or 2 -veined (9/55), or 3 -veined (18/55), or 4–5 -veined (4/55), or 6–7 -veined (1/55). Lower glume lateral veins absent (35/58), or obscure (14/58), or distinct (17/58). Lower glume surface smooth (42/58), or asperulous (1/58), or scabrous (19/58); without pits (58/58); glabrous (50/58), or puberulous (1/58), or pubescent (7/58), or pilose (1/58), or villous (1/58). Lower glume apex acuminate (8/23), or attenuate (7/23), or setaceously attenuate (10/23); muticous (25/31), or awned (6/31). Upper glume subulate (29), or linear (12), or lanceolate (23), or oblong (1); 0.25–1.03–2 length of adjacent fertile lemma; chartaceous (2/38), or herbaceous (1/38), or coriaceous (35/38); with undifferentiated margins (50), or membranous margins (9); without keels (6/16), or 1-keeled (10/16); 0 -veined (2/56), or 1 -veined (44/56), or 2 -veined (9/56), or 3 -veined (18/56), or 4–5 -veined (4/56), or 6–7 -veined (1/56). Upper glume primary vein eciliate (56/58), or ciliolate (1/58), or ciliate (1/58). Upper glume surface smooth (46), or scabrous (15); glabrous (51), or puberulous (1), or pubescent (7), or villous (1). Upper glume apex acuminate (7/23), or attenuate (7/23), or setaceously attenuate (10/23); muticous (25/31), or awned (6/31); 1 -awned (6/6).

FLORETS Fertile lemma lanceolate (55), or elliptic (7), or oblong (4), or ovate (1); membranous (1), or chartaceous (10), or coriaceous (49); of similar consistency on margins (56), or much thinner on margins (3); without keel (47/55), or keeled (8/55); wingless; 5 -veined (54), or 6 -veined (11), or 7 -veined (16), or 8–9 -veined (2), or 10 -veined (1). Lemma lateral veins obscure (13/17), or distinct (2/17), or prominent (2/17); without ribs (58), or ribbed (1). Lemma surface smooth (52), or asperulous (2), or scaberulous (4), or scabrous (5); unwrinkled; without grooves; glabrous (32), or puberulous (9), or pubescent (14), or pilose (8), or villous (3), or hispidulous (2). Lemma margins eciliate (48), or ciliolate (1), or ciliate (7), or pubescent (4). Lemma apex entire (57), or dentate (2); 2 -fid (2/2); acute (24/55), or acuminate (26/55), or attenuate (7/55), or setaceously attenuate (2/55); muticous (22), or mucronate (11), or awned (39); 1 -awned (39/39). Principal lemma awn apical (44/45), or from a sinus (1/45); 0.9–1–1.1 length of lemma. Palea 0.75–0.976–1 length of lemma; 2 -veined (52/52). Palea keels smooth (51), or scaberulous (4), or scabrous (4); eciliate (32), or ciliolate (13), or ciliate (16). Palea surface glabrous (55), or pubescent (2), or pilose (2). Palea apex entire (1/8), or dentate (8/8). Apical sterile florets resembling fertile though underdeveloped (54/54).

FLOWER Lodicules 2 (20/20); membranous (15/16), or scarious (1/16); glabrous (19/20), or ciliate (1/20). Anthers 3 (39/39). Stigmas 2 (17/17). Ovary pubescent on apex (27/27).

FRUIT Caryopsis with adherent pericarp (29/29); linear (2/5), or fusiform (2/5), or ellipsoid (1/5); isodiametric (1/1); smooth (1/1); apex unappendaged (2/2). Embryo 0.2 length of caryopsis. Hilum linear (15/15); 0.9–0.95–1 length of caryopsis.

DISTRIBUTION Europe (7), or Temperate Asia (46), or Tropical Asia (2), or Australasia (3), or North America (12), or South America (3), or Antarctica (1).

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