The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

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

Photo is of parent taxon

common western needlegrass, hairy stiff needlegrass, pubescent western needlegrass, stiff needlegrass, western needlegrass

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.

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.

Spikelets

appressed to the branches.

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.

Caryopses

4-6 mm, fusiform.

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.

2n

=36.

= 36.

Achnatherum occidentale

Achnatherum occidentale subsp. pubescens

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

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. 121. FNA vol. 24, p. 123.
Parent taxa Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum Poaceae > subfam. Pooideae > tribe Stipeae > Achnatherum > Achnatherum occidentale
Sibling taxa
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
A. occidentale subsp. californicum, A. occidentale subsp. occidentale
Subordinate taxa
A. occidentale subsp. californicum, A. occidentale subsp. occidentale, A. occidentale subsp. pubescens
Synonyms Stipa occidentalis, Stipa occidentalis var. montana Stipa occidentalis var. pubescens, Stipa lemmonii var. pubescens, Stipa elmeri
Name authority (Thurb.) Barkworth (Vasey)
Web links