California needlegrass, more...California needlegrass, pubescent western needlegrass, pubescent western needlegrass, western needlegrass, western needlegrass
[Achnatherum nelsonii subsp. longiaristatum (Barkworth & J.R.Maze) Barkworth, moreAchnatherum occidentale (Thurb. ex S.Watson) Barkworth, Achnatherum occidentale subsp. californicum (Merr. & Burtt Davy) Barkworth, Achnatherum occidentale subsp. occidentale , Achnatherum occidentale subsp. pubescens (Vasey) Barkworth, Stipa californica Merr. & Burtt Davy, Stipa columbiana Macoun, Stipa elmeri Piper & Brodie, Stipa minor (Vasey) Scribn., Stipa nelsonii var. longiaristata Barkworth & J.R.Maze, Stipa occidentalis var. californica (Merr. & Burtt Davy) C.L.Hitchc., Stipa occidentalis var. minor (Vasey) C.L.Hitchc., Stipa occidentalis var. pubescens (Vasey) J.R.Maze, Roy L.Taylor & MacBryde]
Plants tightly cespitose, not rhizomatous. Culms 14-120(180) cm tall, 0.3-2 mm thick, inter-nodes glabrous or puberulent to densely pubescent; nodes 2-4, glabrous or pubescent. Basal sheaths glabrous or puberulent to densely pubescent, often ciliate at the throat; collars often with tufts of hair at the sides; ligules 0.2-1.5 mm, often ciliate; blades 0.5-3 mm wide and flat, or convolute and 0.1-0.8 mm in diameter, lax to straight. Panicles 5-30 cm long, 0.5-1.5 cm wide; branches appressed, straight, longest branches 1-7 cm. Spikelets appressed to the branches. Glumes subequal, 9-15 mm long, 0.6-0.9 mm wide; florets 5.5-7.5 mm long, 0.5-0.9 mm thick, fusiform, terete; calluses 0.8-1.2 mm, sharp, dorsal boundary of the glabrous tip with the callus hairs narrowly acute; lemmas evenly hairy, hairs 0.5-1.5 mm at midlength, apical hairs somewhat longer than those below, sometimes similar in length to those at the base of the awns, sometimes longer, apical lobes 0.3-0.5 mm, membranous; awns 15-55 mm, twice-geniculate, first 2 segments evidently hairy, terminal segment glabrous or partly to wholly pilose, sometimes scabrous; paleas 2.2-3.5 mm, 2/5-3/5 as long as the lemmas, hairs at the tip usually shorter than 1 mm, frequently extending beyond the apices, apices rounded; anthers 2.5-3.5 mm, dehiscent, not penicillate. Caryopses 4-6 mm, fusiform. 2n = 36.
Achnatherum occidentale, which extends from British Columbia to California, Utah, and Colorado, varies considerably in pubescence and size. The three subspecies recognized here occasionally occur together.