Trisetum rigidum

HABIT Perennial; caespitose; clumped loosely. Rhizomes elongated. Culms erect, or geniculately ascending; 30–45 cm long; 2–5 -noded. Culm-nodes pubescent. Leaf-sheaths glabrous on surface. Ligule an eciliate membrane; 1.6–3 mm long; lacerate. Leaf-blades 2–6 cm long; 2–4 mm wide; stiff; glaucous. Leaf-blade surface glabrous. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle.

Panicle contracted; elliptic, or oblong; 2.5–8 cm long; 1.5–2.5 cm wide. Primary panicle branches appressed.

Spikelets solitary. Fertile spikelets pedicelled. Pedicels 2.5–7 mm long; glabrous.

FERTILE SPIKELETS Spikelets comprising 2–4 fertile florets; with a barren rhachilla extension. Spikelets oblong; laterally compressed; 8–11 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes villous; with 5–7 mm long hairs. Floret callus bearded.

GLUMES Glumes persistent; similar; shorter than spikelet; thinner than fertile lemma; shiny; gaping. Lower glume lanceolate; 3.8–4.8 mm long; 0.66–0.75 length of upper glume; membranous; purple; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume elliptic; 6–7.7 mm long; 1–1.2 length of adjacent fertile lemma; membranous; purple; 1-keeled; 3 -veined. Upper glume apex acute.

FLORETS Fertile lemma elliptic; 5–7.5 mm long; membranous; much thinner above; much thinner on margins; purple; shiny; keeled; 5 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; geniculate; 4–8 mm long overall; with twisted column. Palea gaping; 4–4.8 mm long; hyaline. Palea keels scaberulous.

FLOWER Anthers 3; 2.2–2.7 mm long. Ovary glabrous.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform.

DISTRIBUTION Europe: eastern. Asia-temperate: Caucasus and western Asia.

NOTES Aveneae. Fl Turk 1993.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.