Achnatherum diegoense
Achnatherum latiglume
San Diego County needlegrass, San Diego needlegrass
Sierra needlegrass, wide-glumed needlegrass
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.
50-110 cm tall, 0.7-1.2 mm thick, lower internodes retrorsely pilose, upper internodes glabrous;
nodes 2-4.
21-25 cm long, (2)4-8 cm wide;
branches strongly divergent to ascending, straight, lower branches 5-7 cm.
15-30 cm long, 0.8-2 cm wide;
branches appressed to strongly ascending, longest branches 2.5-6.5 cm.
appressed to the branches.
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.
subequal, 12-15 mm long, 1.3-1.9 mm wide, 3-veined;
florets 8-9 mm long, 0.9-1.4 mm thick, fusiform, terete;
calluses 0.7-1 mm, blunt to sharp;
lemmas evenly hairy, hairs 0.5-1.5 mm at midlength, apical hairs 1-2 mm, apical lobes to 1 mm, membranous;
awns 33-45 mm, persistent, twice-geniculate, first 2 segments pilose, with hairs 0.5-2 mm, terminal segment mostly scabrous, straight;
paleas 4-5 mm, 3/5 – 4/5 as long as the lemmas, pubescent;
anthers not seen.
not seen.
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 usually retrorsely pubescent, brown to gray-brown, flat when mature;
collars usually glabrous, sometimes with a few hairs at the sides;
basal ligules 0.2-2.5 mm, truncate to rounded;
upper ligules 1.2-3 mm, rounded to acute, ciliate;
blades 0.7-3 mm wide, straight to lax, abaxial surfaces smooth, glabrous, adaxial surfaces pubescent, scabrous.
= unknown.
= 70.
Achnatherum diegoense
Achnatherum latiglume
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 latiglume usually grows on dry slopes in yellow pine forests of southern California. Pohl (1954) demonstrated that it is an alloploid derivative of A. nelsonii and A. lemmonii. He reported being told that it was a fairly common species in the Yosemite Valley, and suggested that the isolated occurrences in Riverside and Fresno counties might represent separate origins of the species.
Achnatherum latiglume resembles A. nevadense and A. occidental, but the latter two species have sharper calluses, and their paleas tend to be thinner and somewhat shorter relative to the lemmas than those of A. latiglume.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CA
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