Achnatherum pinetorum

(M.E. Jones) Barkworth
Common names: Pinewoods needlegrass
Endemic
Synonyms: Stipa pinetorum
Treatment appears in FNA Volume 24. Treatment on page 137.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants tightly cespitose, not rhizomatous. Culms 14-50 (80) cm tall, 0.4-0.9 mm thick, mostly glabrous, lower internodes often puberulent or pubescent, particularly below the nodes; nodes 2-3. Basal sheaths not becoming flat and ribbonlike with age, usually glabrous, throat sometimes with a few hairs, hairs about 0.2 mm; collars glabrous, including the sides; basal ligules 0.2-0.8 mm, truncate to rounded, membranous, glabrous; upper ligules to 2 mm, rounded; blades usually involute and 0.2-0.4 mm in diameter, 0.5-1 mm wide if flat, often arcuate distally, abaxial surfaces scabridulous, adaxial surfaces hairy, hairs about 0.1 mm. Panicles 4.5-20 cm long, 0.5-1 cm wide, contracted; branches appressed, lower branches 1-5 cm, with 2-7 spikelets. Glumes subequal, 7-11 mm long, 0.6-0.9 mm wide, lanceolate, not saccate; florets 3.5-5.5 mm long, 0.6-0.8 mm thick, fusiform, terete; calluses 0.4-0.6 mm, sharp; lemmas densely and evenly pilose, hairs at midlength 1.5-3.5 mm, apical hairs to 5 mm, apical lobes 0.3-2 mm, thin; awns 13-25 mm, persistent, twice-geniculate, first 2 segments scabrous; paleas 2.5-4 mm, from 2/3 as long as to equaling the lemmas, hairy; anthers 1.8-2.6 mm, dehiscent, not penicillate. Caryopses 2.5-4 mm, fusiform. 2n = 32.

Distribution

Colo., N.Mex., Utah, Calif., Oreg., Mont., Wyo., Ariz., Idaho, Nev.

Discussion

Achnatherum pinetorum usually grows on rocky soil, in pinyon-juniper to subalpine associations, at 2100-3300 m. Its range extends from Oregon, Idaho, and Montana south to California, Nevada, and Colorado. It differs from A. webberi in its longer, persistent awns, and from A. lettermanii in its sharp calluses and longer lemma hairs.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum pinetorum"
membranous +  and scarious +
not penicillate +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.26 cm2.6 mm <br />0.0026 m <br />) +
awned +, bifid +, bilobed +  and entire +
Rounded (?) +  and Acute (?) +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Mary E. Barkworth +
(M.E. Jones) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not once-geniculate +
1.3 cm13 mm <br />0.013 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
involute +, convolute +  and flat +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
flexuous +  and straight +
spikelike +
well-developed +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
Pinewoods needlegrass +
branching +  and not branching +
perennial +  and annual +
14 cm140 mm <br />0.14 m <br /> (50 cm500 mm <br />0.5 m <br />) +
intravaginal +  and basal +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
Colo. +, N.Mex. +, Utah +, Calif. +, Oreg. +, Mont. +, Wyo. +, Ariz. +, Idaho +  and Nev. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
sometimes longer +
terete +  and fusiform +
7mm +  and 11mm +
subtending +
lanceolate +
subequal +
membranous +
0.6mm +  and 0.9mm +
divergent +  and distributed +
uncinate +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
solid +  and hollow +
basally concentrated +  and evenly distributed +
0 cm0 mm <br />0 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
ovate +, rectangular +  and lanceolate +
stiffly membranous +  and coriaceous +
pubescent +  and glabrous +
membranous +
membranous +
inconspicuous +
not lobed +
1 cm10 mm <br />0.01 m <br /> (5 cm50 mm <br />0.05 m <br />) +
pubescent +  and puberulent +
concealed +  and prominent +
2 +  and 3 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
not keeled +
reduced +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
4.5cm +  and 20cm +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
dry +  and fleshy +
not prolonged +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa pinetorum +
Achnatherum pinetorum +
Achnatherum +
species +
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 +