Achnatherum occidentale subsp. pubescens

(Vasey)
Common names: Common western needlegrass
Endemic
Synonyms: Stipa occidentalis var. pubescens Stipa lemmonii var. pubescens Stipa elmeri
Treatment appears in FNA Volume 24. Treatment on page 123.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Culms 32-120 cm tall, 0.8-1.3 (2) mm thick, basal internodes puberulent to pubescent. Basal 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. Panicles 10-30 cm; longest branches 2-7 cm. Glumes 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. 2n = 36.

Discussion

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.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number."prolonged" is not a number.

membranous +  and scarious +
pubescent +  and pilose +
not penicillate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
awned +, bifid +, bilobed +  and entire +
0 cm0 mm <br />0 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
Mary E. Barkworth +
(Vasey) +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not once-geniculate +
2.4 cm24 mm <br />0.024 m <br /> (5 cm50 mm <br />0.05 m <br />) +
keeled +  and rounded +
glabrous +  and pubescent +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
straight +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
not evident +
convolute +  and flat +
1mm;3mm +
spikelike +
well-developed +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
Common western needlegrass +
branching +  and not branching +
perennial +  and annual +
32 cm320 mm <br />0.32 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
intravaginal +  and basal +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
Utah +, Wash. +, Colo. +, Mont. +, Alta. +, B.C. +, Idaho +, Calif. +, Wyo. +, Ariz. +, Nev. +  and Oreg. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.55 cm5.5 mm <br />0.0055 m <br /> (0.75 cm7.5 mm <br />0.0075 m <br />) +
sometimes longer +
terete +  and fusiform +
9mm +  and 15mm +
subtending +
obtuse +, acute +  and acuminate +
subequal +
membranous +
0.6mm +  and 0.9mm +
divergent +  and distributed +
uncinate +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
solid +  and hollow +
puberulent +  and densely pubescent +
basally concentrated +  and evenly distributed +
0 cm0 mm <br />0 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
glabrous +  and hairy +
ovate +, rectangular +  and lanceolate +
stiffly membranous +  and coriaceous +
pubescent +  and glabrous +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
membranous +
membranous +
inconspicuous +
not lobed +
2 cm20 mm <br />0.02 m <br /> (7 cm70 mm <br />0.07 m <br />) +
concealed +  and prominent +
pubescent +  and glabrous +
2 +  and 4 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
2/5 +  and 3/5 +
not keeled +
reduced +
0.22 cm2.2 mm <br />0.0022 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
5cm +  and 30cm +
10 cm100 mm <br />0.1 m <br /> (30 cm300 mm <br />0.3 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
dry +  and fleshy +
not prolonged +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa occidentalis var. pubescens +, Stipa lemmonii var. pubescens +  and Stipa elmeri +
Achnatherum occidentale subsp. pubescens +
Achnatherum occidentale +
subspecies +
membranous +
inconspicuous +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
plant +  and cespitose +
aquatic +  and terrestrial +