Achnatherum lettermanii

(Vasey) Barkworth
Common names: Letterman’s needlegrass
Endemic
Synonyms: Stipa lettermanii
Treatment appears in FNA Volume 24. Treatment on page 118.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants tightly cespitose, not rhizomatous. Culms 15-90 cm tall, 0.5-0.8 mm thick, usually glabrous, sometimes puberulent to 5 mm below the lower nodes; nodes 2-3. Basal sheaths smooth, glabrous, margins not ciliate; collars, including the sides, glabrous or sparsely pubescent, collars of the flag leaves glabrous; ligules 0.2-1.5 (2) mm, without tufts of hair on the sides, truncate to rounded; blades 0.5-2, wide, abaxial surfaces smooth to scabridulous, adaxial surfaces scabrous or puberulent. Panicles 7-19 cm long, 0.5-1 cm wide; branches straight, appressed to strongly ascending, longest branches 1.2-2.5 cm. Spikelets appressed to the branches. Glumes 6.5-9 mm, subequal; lower glumes 1 (3) -veined; upper glumes to 0.5 mm shorter than the lower glumes, 0.6-1 mm wide, 1-veined; florets 4.5-6 mm long, 0.8-1 mm thick, fusiform, teret, widest below midlength; calluses 0.4-1 mm, blunt; lemmas evenly hairy, hairs at midlength about 0.5 mm, apical hairs 0.7-1.5 (2) mm, apical lobes 0.3-0.8, membranous, flexible; awns 12-25 mm, persistent, twice-geniculate, scabrous, terminal segment straight; paleas 3-4 mm, 3/4 - 4/5 (9/10) as long as the lemmas, veins terminating at or before the apices, apices round, flat, apical hairs 0.5-1 mm, extending beyond the palea body; anthers 1.5-2 mm, dehiscent, not penicillate. Caryopses about 4 mm, fusiform. 2n = 32.

Distribution

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

Discussion

Achnatherum lettermanii grows in meadows and on dry slopes, from sagebrush to subalpine habitats, at 1700-3400 m. Its range extends from Oregon and Montana to southern California, Arizona, and New Mexico; it is not known from Mexico. When sympatric with A. nelsonii, A. lettermanii tends to grow in shallower or more disturbed soils. It can be distinguished from that species by its generally finer leaves and more tightly cespitose growth habit, as well as its blunter calluses and longer paleas. Its relatively long paleas also distinguish A. lettermanii from A. perplexum.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum lettermanii"
smooth +  and scabridulous +
membranous +  and scarious +
puberulent +  and scabrous +
not penicillate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
awned +, bifid +, bilobed +  and entire +
Rounded (?) +  and Acute (?) +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.3 +  and 0.8 +
Mary E. Barkworth +
(Vasey) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not once-geniculate +
1.2 cm12 mm <br />0.012 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 +
0.5 (?) +  and 2 (?) +
involute +, convolute +  and flat +
appressed;strongly ascending +
spikelike +
well-developed +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
glabrous +  and pubescent +
Letterman’s needlegrass +
branching +  and not branching +
perennial +  and annual +
15 cm150 mm <br />0.15 m <br /> (90 cm900 mm <br />0.9 m <br />) +
intravaginal +  and basal +
puberulent +  and glabrous +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
not woody +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-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 +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
sometimes longer +
fusiform +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
subequal +
0.65 cm6.5 mm <br />0.0065 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
membranous +
divergent +  and distributed +
uncinate +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 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 +
truncate +  and rounded +
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 +
1.2 cm12 mm <br />0.012 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
concealed +  and prominent +
2 +  and 3 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
3/4 +  and 4/59/10 +
not keeled +
reduced +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
7cm +  and 19cm +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
dry +  and fleshy +
not prolonged +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa lettermanii +
Achnatherum lettermanii +
Achnatherum +
species +
membranous +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
0.6mm +  and 1mm +
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 +