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San Diego County needlegrass, San Diego needlegrass

common western needlegrass, stiff needlegrass, velvet-leaf, western needle grass

Habit Plants cespitose, not rhizomatous. Plants tightly 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.

14-120(180) cm tall, 0.3-2 mm thick, internodes glabrous or puberulent to densely pubescent;

nodes 2-4, glabrous or pubescent.

Panicles

21-25 cm long, (2)4-8 cm wide;

branches strongly divergent to ascending, straight, lower branches 5-7 cm.

5-30 cm long, 0.5-1.5 cm wide;

branches appressed, straight, longest branches 1-7 cm.

Spikelets

appressed to the branches.

appressed to the branches.

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.

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.

Caryopses

4-6 mm, fusiform.

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 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.

2n

= unknown.

=36.

Achnatherum diegoense

Achnatherum occidentale

Distribution
from FNA
CA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
[WildflowerSearch map]
[BONAP county map]
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 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.)

Key
1. Terminal awn segment usually pilose; culms 0.3-1 mm thick, glabrous even on the basal internodes; glumes often purplish
subsp. occidentale
1. Terminal awn segment usually scabrous or glabrous, occasionally pilose at the base; culms 0.5-2 mm thick; glumes usually green.
→ 2
2. First 2 awn segments scabrous or pilose with hairs of mixed lengths; apical lemma hairs longer than the basal awn hairs
subsp. californicum
2. First 2 awn segments pilose, the hairs gradually and evenly becoming shorter towards the first geniculation; apical lemma hairs similar in length to the basal awn hairs
subsp. pubescens
Source FNA vol. 24, p. 131. FNA vol. 24, p. 121.
Parent taxa Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum
Sibling taxa
A. aridum, A. arnowiae, A. contractum, A. coronatum, A. curvifolium, A. eminens, A. hendersonii, A. hymenoides, A. latiglume, A. lemmonii, A. lettermanii, A. lobatum, A. nelsonii, A. nevadense, A. occidentale, A. parishii, A. perplexum, A. pinetorum, A. richardsonii, A. robustum, A. scribneri, A. splendens, A. stillmanii, A. swallenii, A. thurberianum, A. wallowaense, A. webberi, A. ×bloomeri
A. aridum, A. arnowiae, A. contractum, A. coronatum, A. curvifolium, A. diegoense, A. eminens, A. hendersonii, A. hymenoides, A. latiglume, A. lemmonii, A. lettermanii, A. lobatum, A. nelsonii, A. nevadense, A. parishii, A. perplexum, A. pinetorum, A. richardsonii, A. robustum, A. scribneri, A. splendens, A. stillmanii, A. swallenii, A. thurberianum, A. wallowaense, A. webberi, A. ×bloomeri
Subordinate taxa
A. occidentale subsp. californicum, A. occidentale subsp. occidentale, A. occidentale subsp. pubescens
Synonyms Stipa occidentalis, Stipa occidentalis var. montana
Name authority (Swallen) Barkworth (Thurb.) Barkworth
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