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.

Thrasya

HABIT Annual (1), or perennial (21). Culms erect (19/21), or geniculately ascending (10/21), or decumbent (4/21), or rambling (1/21); robust (1/2), or slender (1/2); 10–66.69–200 cm long; without nodal roots (2/2), or rooting from lower nodes (2/2). Lateral branches lacking (3/4), or ample (1/4). Ligule an eciliate membrane. Leaf-blades linear (20), or lanceolate (6).

INFLORESCENCE Inflorescence composed of racemes; terminal (14), or terminal and axillary (8).

Racemes single, or paired (2), or borne along a central axis (1); unilateral. Rhachis narrowly winged (9), or broadly winged (13); not appreciably folded (4), or folded longitudinally to embrace spikelets (18); terminating in a spikelet (2), or barren extension (20); extension flattened (20/20). Spikelet packing alternately adaxial and abaxial; 1 -rowed.

Spikelets pectinate (20/20); in pairs. Fertile spikelets sessile and pedicelled (21), or pedicelled (1); 2 in the cluster. Pedicels fused to internode; reduced to a stump (1/1).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic, or oblong (4), or ovate (1); dorsally compressed; 0.9–2.937–5.5 mm long; falling entire. Spikelet callus brief (19), or square (3); pubescent (3/3).

GLUMES Glumes both absent or obscure (1), or one the lower absent or obscure (5), or two (18); shorter than spikelet (15/21), or reaching apex of florets (6/21); thinner than fertile lemma (21/21). Lower glume lanceolate (1/18), or ovate (8/18), or oblate (9/18); hyaline (14/18), or membranous (4/18); without keels (18/18); 0 -veined (16/17), or 1 -veined (5/17). Lower glume lateral veins absent (17/18), or distinct (1/18). Lower glume surface without pits (18/18); glabrous (17/18), or puberulous (1/18), or pubescent (1/18), or pilose (1/18). Lower glume apex truncate (5/17), or obtuse (5/17), or acute (7/17); muticous (18/18), or awned (1/18). Upper glume lanceolate (3/21), or elliptic (16/21), or ovate (1/21), or oblate (1/21); 1–1.05–1.1 length of adjacent fertile lemma; hyaline (1/21), or membranous (12/21), or chartaceous (8/21); without keels (21/21); 0 -veined (1/20), or 1–2 -veined (3/20), or 3 -veined (2/20), or 4 -veined (1/20), or 5 -veined (11/20), or 6 -veined (2/20), or 7 -veined (4/20). Upper glume lateral veins without cross-veins (1/2), or transversely connected at apex (1/2), or with cross-veins (1/2). Upper glume surface smooth (20/21), or asperulous (1/21); glabrous (15/21), or pubescent (1/21), or pilose (9/21); with simple hairs (8/9), or tubercle-based hairs (1/9). Upper glume apex entire (19/21), or erose (1/21), or dentate (1/21); 2 -fid (1/1); emarginate (3/20), or truncate (2/20), or obtuse (3/20), or acute (13/20), or attenuate (1/20).

FLORETS Basal sterile florets male (16), or barren (6); with palea (18), or without significant palea (4). Lemma of lower sterile floret lanceolate (1), or elliptic (17), or oblong (11), or obovate (1); 1.2 length of fertile lemma; hyaline (2), or membranous (1), or chartaceous (3), or coriaceous (16); 3 -veined (1/6), or 4 -veined (3/6), or 5 -veined (2/6); without grooves (4), or sulcate (18), or readily splitting into two halves (15); obtuse (2/20), or acute (18/20). Palea of lower sterile floret hyaline (1/18), or membranous (1/18), or becoming indurate on flanks at maturity (16/18). Fertile lemma elliptic (20), or oblong (1), or ovate (2); coriaceous; without keel; wingless; 5 -veined (1/1). Lemma surface smooth (4), or papillose (14), or striate (14), or punctate (1); unwrinkled; without grooves; without hair tufts (16), or with conspicuous apical hairs (6). Lemma margins involute; eciliate (20), or ciliolate (1), or ciliate (2). Lemma apex obtuse (1), or acute (21); without ornament (16), or pubescent (6). Palea coriaceous.

FLOWER Lodicules 2 (16/16); fleshy (16/16); truncate (16/16). Anthers 2 (1/18), or 3 (17/18).

FRUIT Caryopsis ellipsoid (1/1). Embryo 0.4–0.45–0.5 length of caryopsis. Hilum linear (1/1).

DISTRIBUTION North America (1), or South America.

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