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.

Tristachya

HABIT Annual (1), or perennial (20). Rhizomes absent (15), or short (4), or elongated (2). Culms erect (20), or geniculately ascending (1), or decumbent (1); 20–97.2–270 cm long. Lateral branches lacking (5/6), or sparse (2/6). Ligule a fringe of hairs. Leaf-blades filiform (3), or linear (18); herbaceous (19), or coriaceous (2); stiff (4), or firm (17). Leaf-blade margins cartilaginous (1/1).

INFLORESCENCE Inflorescence a panicle (20), or composed of racemes (1); exserted (20), or embraced at base by subtending leaf (1).

Panicle open (14/19), or contracted (6/19). Primary panicle branches not whorled (20/20), or whorled at lower nodes (1/20).

Racemes single (1/1); bilateral (1/1); bearing few fertile spikelets (1/1); bearing 3–24 fertile spikelets on each (1/1). Rhachis angular (1/1).

Spikelets appressed (1/1); in pairs (3), or in threes (20). Fertile spikelets pedicelled; 2 in the cluster (3), or 3 in the cluster (20); subequal (2/2). Pedicels free (8), or fused to each other (13); filiform (3/3), or linear (1/3).

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate; of unremarkable solid shape (20), or turbinate (1); laterally compressed; 8–22.92–45 mm long; breaking up at maturity; disarticulating below each fertile floret. Floret callus elongated; pubescent (14/20), or pilose (1/20), or bearded (5/20); acute (1), or pungent.

GLUMES Glumes persistent; shorter than spikelet (3), or reaching apex of florets (1), or exceeding apex of florets (18). Lower glume lanceolate (17), or elliptic (3), or ovate (1); chartaceous (19), or coriaceous (2); without keels; 3 -veined. Lower glume surface smooth, or asperulous (1); without pits; glabrous (14), or pilose (2), or hispidulous (1), or setose (9). Lower glume apex acute (14), or acuminate (6), or attenuate (3), or setaceously attenuate (3). Upper glume lanceolate; chartaceous; without keels; 3 -veined. Upper glume surface glabrous, or setose (1); with tubercle-based hairs (1/1). Upper glume apex entire, or dentate (1); 2 -fid (1/1); obtuse (8/20), or acute (10/20), or acuminate (3/20), or attenuate (1/20).

FLORETS Basal sterile florets male, or barren (1); with palea. Lemma of lower sterile floret lanceolate; chartaceous; 3 -veined (1/20), or 5–7 -veined (19/20); acute (19), or acuminate (3). Fertile lemma elliptic (1), or oblong (20); coriaceous; without keel; wingless; 5 -veined (1/15), or 7 -veined (11/15), or 9 -veined (3/15). Lemma surface unwrinkled; without grooves; glabrous (4), or pubescent (15), or pilose (2); hairy on back (16/17), or in lines (1/17); without hair tufts (18), or with a transverse row of hair tufts (3). Lemma margins involute; interlocking with palea keels. Lemma apex dentate (2), or lobed (19); 2 -fid; incised 0.2–0.2643–0.4 of lemma length; acute (3/4), or setaceously attenuate (1/4); awned; 1 -awned (11), or 3 -awned (10). Principal lemma awn from a sinus; geniculate. Lateral lemma awns shorter than principal (6/6). Palea membranous (20), or coriaceous (1); 2 -veined. Palea keels approximate; unthickened (2), or thickened (19); wingless (13), or winged (8). Palea surface glabrous (18), or pubescent (3).

FLOWER Anthers 3 (20/20). Ovary glabrous (3/14), or pubescent on apex (11/14).

FRUIT Caryopsis with adherent pericarp (20/20); linear (2/2). Hilum linear (2/2).

DISTRIBUTION Africa (17), or North America (3), or South America (2).

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