Muhlenbergia fragilis
Plants annual. Culms 10-38 cm, erect or spreading; internodes mostly glabrous, smooth or scabridulous, scabrous or strigulose below the nodes. Sheaths often longer than the internodes, scabridulous, margins hyaline; ligules 1-3 mm, hyaline, obtuse, irregularly toothed to lacerate, with lateral lobes; blades 1-10 cm long, 0.4-2 mm wide, flat, scabrous abaxially, strigulose adaxially, margins and midveins thickened basally, whitish. Panicles 10-24 cm long, 3.5-11 cm wide, diffuse; primary branches 2.2-6.2 cm long, about 0.1 mm thick, diverging 80-100° from the rachises, straight; pedicels 6-10 mm long, about 0.02 mm thick, delicate; disarticulation above the glumes. Spikelets 1-1.2 mm, appressed to slightly divergent. Glumes equal to subequal, 0.5-1 mm, glabrous throughout or obscurely puberulent, hairs about 0.06 mm, 1-veined, obtuse or subacute; lemmas 1-1.2 mm, oblongelliptic, purplish to light brownish, not mottled, glabrous or densely appressed-puberulent on the margins and midveins, apices obtuse, unawned; paleas 0.9-1.2 mm, oblongelliptic; anthers 0.3-0.5 mm, purplish. Caryopses 0.7-0.9 mm, elliptic, reddish-brown. 2n = 20.
Distribution
Calif., Ariz., N.Mex., Nev., Tex.
Discussion
Muhlenbergia fragilis grows on rocky talus slopes, cliffs, canyon walls, road cuts, and sandy slopes, often over calcareous parent materials, at elevations of 480-2200 m. It is usually found in oak-gramma savannahs, thorn scrub forests, oak-yellow pine forests, and pinyon-juniper woodlands. Its range extends from the southwestern United States to southern Mexico.
Populations may have individual plants with completely glabrous lemmas or may consist entirely of such plants. This morphological variation is not correlated with any distributional or habitat characteristics.
Selected References
None.
Lower Taxa
"decumbent" is not a number.