UW Burke Herbarium species comparison

Sheaths open, usually glabrous;

auricles well-developed;

ligules 0.5-1.5 mm. long, with fine marginal hairs;

blades flat, coarse, usually scabrous, 7-15 mm. broad, often glaucous.

Sheaths open;

auricles less than 1 mm. long, sometimes lacking;

ligules membranous, barely 0.5 mm. long;

blades flat to folded or involute, 1-4 mm. broad.

Inflorescence a single terminal spike 10-20 cm. long, often drooping, the upper spikelets crowded, the lower barely overlapping;

spikelets articulate above the glumes, 2- to 6-flowered, borne flatwise on the rachis, 2 per node;

glumes scabrous, hardened, the base spreading, the awn slender and divergent;

lemmas scabrid-pubescent, the body 10-15 mm. long, tapered gradually into a divergent, scabrid awn up to 3.5 cm. long;

paleas nearly as long as the body of the lemmas.

Inflorescence a single terminal spike 3-15 cm. long, often partly included in the upper sheath, the rachis readily disarticulating;

spikelets 1- to 6-flowered, usually 2 per node, borne flatwise on the rachis;

glumes 1- or 2-nerved, simple to bifid, tapering to 1-2 divaricate awns 3-10 cm. long;

florets varying from all fertile to all but one sterile;

lemmas scabrous to puberulent, 5-nerved, the main nerve extending into an awn about equal to the glumes, the 2 lateral nerves often extended and bristle-like;

paleas 2-nerved, the nerves often extended into bristles up to 5 mm. long.