Achnatherum occidentale |
Achnatherum diegoense |
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common western needlegrass, stiff needlegrass, velvet-leaf, western needle grass |
San Diego County needlegrass, San Diego needlegrass |
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Habit | Plants tightly cespitose, not rhizomatous. | Plants 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. |
110-140 cm tall, 2.5-4 mm thick, internodes densely and retrorsely pubescent for 3-9 mm below the nodes, particularly the lower nodes, glabrous or retrorsely puberulent elsewhere; nodes 3, pubescent or glabrate. |
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Panicles | 5-30 cm long, 0.5-1.5 cm wide; branches appressed, straight, longest branches 1-7 cm. |
21-25 cm long, (2)4-8 cm wide; branches strongly divergent to ascending, straight, lower branches 5-7 cm. |
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Spikelets | appressed to the branches. |
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. |
subequal, 8-11.5 mm; lower glumes 0.5-1 mm wide, 3-5-veined; upper glumes 3-veined; florets 5.5-7.5 mm long, 0.7-1 mm thick, fusiform, terete; calluses 0.25-1.2 mm, acute; lemmas evenly hairy, hairs at midlength and at the apices 0.5-1 mm, apical lobes 0.2-0.4 mm, membranous, flexible; awns 20-50 mm, persistent, twice-geniculate, all segments scabrous to scabridulous, terminal segment straight; paleas 2.6-3.8 mm, 1/2 - 3/4 as long as the lemmas, pubescent, hairs not extending beyond the apices, veins terminating below the apices, apices rounded; anthers 2.5-4 mm, dehiscent, not penicillate. |
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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 mostly glabrous or puberulent, margins ciliate distally; collars glabrous or with hairs, hairs mostly to 0.5 mm, sides with tufts of 1.5-2 mm hairs; ligules 0.4-2 mm, rounded to acute, abaxial surfaces hairy, hairs to 0.5 mm; upper ligules 1-3 mm, similar in structure and pubescence; blades 1-3.5 mm wide, abaxial surfaces smooth or scabrous, adaxial surfaces prominently ribbed, hairy, hairs 2-3 mm. |
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2n | =36. |
= unknown. |
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Achnatherum occidentale |
Achnatherum diegoense |
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Distribution |
AZ; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
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CA
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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 diegoense grows in chaparral and coastal sage scrub, on rocky soil near streams or the coast, at 0-350 m, on the Channel Islands of Santa Barbara County, California, and, on the mainland, in Ventura and San Diego counties south into Baja California, Mexico. (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. 131. | ||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Stipa occidentalis, Stipa occidentalis var. montana | |||||||||
Name authority | (Thurb.) Barkworth | (Swallen) Barkworth | ||||||||
Web links |
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