Achnatherum thurberianum

(Piper) Barkworth
Common names: Thurber's needlegrass
Endemic
Synonyms: Stipa thurberiana
Treatment appears in FNA Volume 24. Treatment on page 125.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants cespitose, not rhizomatous. Culms 30-75 cm tall, 0.5-1.7 mm thick, internodes pubescent or glabrous, pubescence more common on the lower internodes, particularly just below the nodes; nodes 2-3, lower nodes retrorsely pubescent, upper nodes glabrous or pubescent. Basal sheaths glabrous, usually smooth, brown or gray-brown; collars glabrous, without tufts of hair at the sides; basal ligules 1.5-6 mm, hyaline, rounded to acute, lacerate; upper ligules to 8 mm, hyaline, acute, glabrous; blades 0.5-2 mm wide, convolute, abaxial surfaces scabrous, adaxial surfaces scabrous or hairy, hairs about 0.3 mm. Panicles 7-15 cm long, 0.5-2.5 cm wide, often included in the upper leaf-sheaths at the start of anthesis; branches 1.5-6 cm, appressed to strongly ascending, with 1-6 spikelets. Glumes often purplish; lower glumes 10-15 mm long, 1.2-2 mm wide; upper glumes to 2 mm shorter; florets 6-9 mm long, 0.7-1.2 mm thick, fusiform, terete; calluses 0.9-1.5 mm, sharp; lemmas coriaceous, evenly pubescent or the back glabrate distally, hairs 0.5-0.8 mm, apices lobed on 1 margin, lobe about 0.1 mm long, thick, apical lemma hairs 0.5-0.8 mm; awns 32-56 mm, twice-geniculate, first 2 segments pilose, hairs 0.8-2 mm, terminal segment glabrous, often scabrous; paleas 4.6-6.1 mm, 3/4 - 9/10 as long as the lemmas, sparsely pubescent towards the base; anthers 2.5-3.5 mm, dehiscent, not penicillate. Caryopses 5-7 mm, fusiform. 2n =34.

Distribution

Wash., Utah, Calif., Colo., Oreg., Mont., Wyo., Idaho, Nev.

Discussion

Achnatherum thurberianum grows in canyons and foothills, primarily in sagebrush desert and juniper woodland associations, from Washington to southern Idaho and southwestern Montana and from California to Utah, at 900-3000 m. Its long ligules and pilose awns make it one of the easier North American species of Achnatherum to identify.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum thurberianum"
membranous +  and scarious +
hairy +  and scabrous +
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 +
(Piper) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not once-geniculate +
3.2 cm32 mm <br />0.032 m <br /> (5.6 cm56 mm <br />0.056 m <br />) +
keeled +  and rounded +
gray-brown +  and brown +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
involute +, convolute +  and flat +
0.5mm;2mm +
flexuous +  and straight +
appressed;strongly ascending +
spikelike +
well-developed +
0.09 cm0.9 mm <br />9.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
Thurber's needlegrass +
branching +  and not branching +
perennial +  and annual +
30 cm300 mm <br />0.3 m <br /> (75 cm750 mm <br />0.75 m <br />) +
intravaginal +  and basal +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.17 cm1.7 mm <br />0.0017 m <br />) +
Wash. +, Utah +, Calif. +, Colo. +, Oreg. +, Mont. +, Wyo. +, Idaho +  and Nev. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.6 cm6 mm <br />0.006 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
sometimes longer +
terete +  and fusiform +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
membranous +
divergent +  and distributed +
uncinate +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
solid +  and hollow +
common +, glabrous +  and pubescent +
basally concentrated +  and evenly distributed +
0 cm0 mm <br />0 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
glabrate +  and pubescent +
ovate +, rectangular +  and lanceolate +
coriaceous +
pubescent +  and glabrous +
membranous +
0.1 cm1 mm <br />0.001 m <br /> (?) +
membranous +
inconspicuous +
not lobed +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
1.2mm +  and 2mm +
concealed +  and prominent +
2 +  and 3 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
3/4 +  and 9/10 +
not keeled +
reduced +
0.46 cm4.6 mm <br />0.0046 m <br /> (0.61 cm6.1 mm <br />0.0061 m <br />) +
7cm +  and 15cm +
0.5 cm5 mm <br />0.005 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
dry +  and fleshy +
not prolonged +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa thurberiana +
Achnatherum thurberianum +
Achnatherum +
species +
membranous +
0 cm0 mm <br />0 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
pubescent +  and glabrous +
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 +