Achnatherum diegoense |
Achnatherum aridum |
|
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San Diego County needlegrass, San Diego needlegrass |
arid needlegrass, Mormon needlegrass |
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Habit | Plants cespitose, not rhizomatous. | Plants cespitose, not rhizomatous. |
Culms | 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. |
35-85 cm tall, 0.9-2.5 mm thick, usually glabrous and smooth, sometimes scabridulous or puberulent; nodes 2-3. |
Panicles | 21-25 cm long, (2)4-8 cm wide; branches strongly divergent to ascending, straight, lower branches 5-7 cm. |
5-17 cm long, 1-1.5 cm wide, contracted, bases often enclosed at anthesis; branches appressed or strongly ascending, straight, lower branches 1.5-4 cm. |
Spikelets | appressed to the branches. |
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Glumes | 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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Lower glumes | 8-15 mm long, 0.6-0.8 mm wide; upper glumes 1-5 mm shorter; florets 4-6.5 mm long, 0.6-1.1 mm thick, fusiform, terete; calluses 0.2-1 mm, sharp; lemmas evenly hairy on the lower portion, hairs 0.2-0.5 mm, the distal 1/5 – 1/4 often glabrous, apical hairs absent or fewer than 5, to 1.5 mm; awns 40-80 mm, persistent, obscurely once-geniculate, scabridulous, terminal segment flexuous; paleas 2-3.2 mm, 1/2 - 3/4 as long as the lemmas, pubescent, hairs exceeding the apices, apices rounded, flat; anthers 2-3.5 mm, dehiscent, not penicillate. |
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Basal | 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. |
sheaths glabrous, upper sheath margins hyaline distally; collars of the basal sheaths occasionally with a small tuft of 0.8 mm hair on the sides, collars of the upper leaves glabrous, scabridulous, or sparsely puberulent; ligules 0.2-1.5 mm, truncate to rounded, erose, sometimes ciliate, cilia about 0.05 mm; blades 0.9-3 mm wide, abaxial surfaces smooth or scabridulous, glabrous, adaxial surfaces hirtellous, hairs to 0.5 mm. |
2n | = unknown. |
= unknown. |
Achnatherum diegoense |
Achnatherum aridum |
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Distribution |
CA
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AZ; CA; CO; NM; NV; TX; UT
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Discussion | 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.) |
Achnatherum aridum grows on rocky outcrops, in shrub-steppe and pinyon-juniper associations, from southeastern California to Colorado and New Mexico, at 1200-2000 m. It has also been reported from Texas, but no specimens documenting these reports have been located. It has not been found in Mexico. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 24, p. 131. | FNA vol. 24, p. 131. |
Parent taxa | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum | Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum |
Sibling taxa | ||
Synonyms | Stipa arida | |
Name authority | (Swallen) Barkworth | (M.E. Jones) Barkworth |
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