Achnatherum occidentale |
Achnatherum occidentale subsp. pubescens |
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common western needlegrass, stiff needlegrass, velvet-leaf, western needle grass |
common western needlegrass, hairy stiff needlegrass, pubescent western needlegrass, stiff needlegrass, western needlegrass |
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Habit | Plants tightly cespitose, not rhizomatous. | |||||||||
Culms | 14-120(180) cm tall, 0.3-2 mm thick, internodes glabrous or puberulent to densely pubescent; nodes 2-4, glabrous or pubescent. |
32-120 cm tall, 0.8-1.3(2) mm thick, basal internodes puberulent to pubescent. |
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Panicles | 5-30 cm long, 0.5-1.5 cm wide; branches appressed, straight, longest branches 1-7 cm. |
10-30 cm; longest branches 2-7 cm. |
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Spikelets | appressed to the branches. |
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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 hair, 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. |
usually green; lemmas with apical pubescence similar in length to the basal awn pubescence; awns 24-50 mm, pilose on the first 2 segments, with hairs gradually becoming shorter distally, terminal segment scabrous or glabrous. |
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Caryopses | 4-6 mm, fusiform. |
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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. |
sheaths usually pubescent, sometimes densely pubescent, occasionally glabrous; collars often with tufts of hair at the sides; blades 1-3 mm wide, adaxial surfaces pubescent to pilose. |
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2n | =36. |
= 36. |
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Achnatherum occidentale |
Achnatherum occidentale subsp. pubescens |
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Distribution |
AZ; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
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Discussion | 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Achnatherum occidentale subsp. pubescens grows from Washington to California and eastward to Wyoming, at 1300-4700 m. It is the most widespread and variable subspecies of A. occidentale, intergrading with subsp. californicum, A. nelsonii, and A. lettermanii. It differs from the latter two in its shorter paleas and its pilose awns. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 121. | FNA vol. 24, p. 123. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum > Achnatherum occidentale | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Stipa occidentalis, Stipa occidentalis var. montana | Stipa occidentalis var. pubescens, Stipa lemmonii var. pubescens, Stipa elmeri | ||||||||
Name authority | (Thurb.) Barkworth | (Vasey) | ||||||||
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