Achnatherum robustum
Achnatherum pinetorum
sleepy grass
pine needlegrass, pine-forest needle grass, pinewoods needlegrass
100-230 cm tall, 2-4.5 mm thick, mostly glabrous, often pubescent below the nodes, the pubescence antrorse or retrorse;
nodes 4-5.
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.
15-30 cm long, 0.8-3.5 cm wide;
branches straight, appressed to ascending, lower branches 3-9 cm.
4.5-20 cm long, 0.5-1 cm wide, contracted;
branches appressed, lower branches 1-5 cm, with 2-7 spikelets.
appressed to the branches.
subequal, 9-11.5 mm long, 1-1.4 mm wide;
florets 5.9-8.5 mm long, 0.9-1.2 mm thick, fusiform, terete;
calluses 0.3-1 mm, blunt;
lemmas evenly hairy, hairs at midlength 0.3-0.8 mm, apical hairs to 1.5 mm;
awns 20-32 mm, persistent, twice-geniculate, scabridulous to scabrous, scabrules to about 0.1 mm, longest on the middle segment, terminal segment straight;
paleas 3.7-5.6 mm, 2/3 - 3/4 as long as the lemmas, hairy, hairs about 0.5 mm, not exceeding the apices, veins terminating below the apices, apices rounded;
anthers 4-5 mm, dehiscent, penicillate.
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.
5-6 mm.
2.5-4 mm, fusiform.
sheaths mostly glabrous, margins usually ciliate distaily;
collars hairy, those of the flag leaves densely hairy, hairs 0.5-2 mm, sides glabrous;
basal ligules 1-2 mm;
upper ligules to 4 mm, truncate, rounded, or obtuse, glabrous;
blades 6-10 mm wide, glabrous, abaxial surfaces smooth, adaxial surfaces prominently ribbed, ribs scabrous.
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.
= 64.
= 32.
Achnatherum robustum
Achnatherum pinetorum
Achnatherum robustum grows on dry plains and hills, in open woods and forest clearings, and along roadsides, from Wyoming through Colorado to Arizona, New Mexico, and northern Mexico. Records from Kansas represent recent introductions; it is not clear whether the species has persisted there. Achnatherum robustum is sometimes confused with A. nelsonii subsp. dorei and Nassella viridula; it differs from both in the densely hairy collars of its flag leaves. Although not widely available, it has potential as an ornamental grass, particularly in arid regions with cold winters.
The English-language name refers to the effect some samples, particularly those from the Sacramento and Sierra Blanca mountains, New Mexico, have on livestock, especially horses and cattle. "Mildly poisoned animals are dejected, inactive, and withdrawn; severely poisoned animals lie on their sides in a profound slumber" (Cheeke and Shull 1985). The active ingredient is diacetone alcohol (Epstein et al 1964).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
KS Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
CA
OR
Flora NW
PNW Herbaria
