Plants perennial; cespitose, rhizomatous. Culms
30-60 cm, erect, geniculate at the middle nodes; nodes glabrous or pubescent,
hairs to 0.3 mm. Sheaths glabrous or sparsely pilose on the margins;
ligules 0.5-2 mm, lacerate; blades 2-15 cm long, 2-4 mm wide,
mostly scabrous on both surfaces, with papillose-based hairs behind the ligules.
Panicles 4-8 cm; fascicles 5-8 mm. Lateral spikelets with
1 or 2(4) staminate florets; glumes not conspicuously fused basally,
thin, papery, flabellate, dorsally awned, awns not exceeding the apices, apical
lobes rounded, ciliate to finely laciniate, veins not or scarcely excurrent;
anthers 3, 2.5-3.5 mm. Central spikelets with 1 bisexual floret;
glumes with 1 or more divergent, dorsal awns, apical lobes, ciliate to
finely laciniate, veins excurrent; lemmas exceeding the glumes, bilobed,
mucronate. 2n = 36, 54.
Hilaria mutica grows in level upland areas and desert valleys subject
to occasional flooding but lacking permanent streams. Its range extends into
northern Mexico. Although H. mutica has moderate forage value, its palatability
is low and it is frequently infected with ergot.
FNA 2003, Gould 1980
Common Name: tobosagrass Duration: Perennial Nativity: Native Lifeform: Graminoid General: Rhizomatous perennial grass; stems 30-60 cm, erect, geniculate at the middle nodes, slender, tough and wiry; glabrous or scabrous-puberulent at the nodes. Vegetative: Sheaths glabrous or sparsely pilose on the margins, blades 2-4 mm wide, 5-10 cm long, flat or rolled, glabrous to scabrous with papillose-based hairs behind the ligules; ligules 0.5-2 mm, lacerate with few hairs 2 mm behind the ligule; collar margins vill Inflorescence: Spikes 4-8 cm long with 8-25 spikelet clusters, these mostly 6-9 mm long; the clusters have 3 spikelets and disarticulate as a unit, leaving zig-zag rachises; the three spikelets are subequal, with tuft of hairs mostly 1-3 mm long at the base; glumes thin, papery, dorsally awned, awns not exceeding apices, veins excurrent; lemmas longer than glumes. Ecology: Found on dry, exposed, sandy to rocky slopes and plains, from 2,000-6,000 ft (610-1829 m); flowers throughout the year. Distribution: CA, AZ, NM, w TX; south to c MEX. Notes: The genus is distinguished by the rigid inflorescence spikes which produce groups of 3 sessile, awned spikelets, that when mature, have conspicuous tan-white papery bracts (glumes) which often splay out. The 3 spikelets fall as a unit and leave a characteristic zig-zag naked seed stalk. H. mutica distinguished by lacking stolons, having thick rhizomes and robust, thick, rigid leaves and leaf bases. The culms are not felty pubescent as in H. rigida and the glumes are conspicuously widened toward the apex, unlike H. jamesii. Very drought tolerant, this species has the ability to become totally dormant as soil moisture drops. Ethnobotany: Unknown Etymology: Hilaria is named for Auguste St. Hilaire (1779-1853), a French naturalist; mutica means blunt, probably referring to the shape of the glumes. Synonyms: Pleuraphis mutica Editor: SBuckley 2010, FSCoburn 2014, AHazelton 2015