Trisetum cernuum

HABIT Perennial; caespitose. Culms 50–110 cm long. Culm-internodes distally glabrous. Leaf-sheaths scaberulous; glabrous on surface to pilose. Ligule an eciliate membrane; 1.5–3 mm long; erose; truncate, or acute. Leaf-blades 5–10 mm wide. Leaf-blade surface scaberulous.

INFLORESCENCE Inflorescence a panicle.

Panicle open; pyramidal; 10–30 cm long; bearing few spikelets. Primary panicle branches spreading, or drooping; whorled at most nodes. Panicle branches capillary; flexuous; scabrous.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with diminished florets at the apex. Spikelets oblong; laterally compressed; 6–12 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes 2 mm long; pilose; with 2 mm long hairs. Floret callus pubescent.

GLUMES Glumes persistent; dissimilar; shorter than spikelet; thinner than fertile lemma; shiny. Lower glume linear; 1–2 mm long; 0.25–0.5 length of upper glume; membranous; 1-keeled; 1 -veined. Lower glume lateral veins absent. Lower glume apex acuminate. Upper glume linear; 3.5–4 mm long; 0.66–0.75 length of adjacent fertile lemma; membranous; 1-keeled; 3 -veined. Upper glume apex erose; acute.

FLORETS Fertile lemma ovate; 5–6 mm long; membranous; keeled; 5 -veined. Lemma apex dentate; 2 -fid; awned; 1 -awned. Principal lemma awn dorsal; arising 0.5–0.66 way up back of lemma; flexuous; 10 mm long overall. Palea gaping; hyaline. Rhachilla extension pilose. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Anthers 3; 1 mm long. Ovary pubescent on apex.

FRUIT Caryopsis with adherent pericarp. Hilum punctiform. Endosperm soft.

DISTRIBUTION North America: Subarctic, western Canada, northwest USA, and southwest USA. South America: southern South America.

NOTES Aveneae. Fl Pac NW 1994.

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