Muhlenbergia arsenei A.S. Hitchc.
Family: Poaceae
Navajo Muhly
Muhlenbergia arsenei image
Liz Makings  

Plants perennial; rhizomatous, rhizomes sometimes short and the plants loosely cespitose. Culms 10-50 cm tall, 0.4-1 mm thick, decumbent; internodes glabrous or strigulose. Sheaths shorter than the internodes, strigulose or glabrous, usually without necrotic spots, not becoming spirally coiled when old; ligules 1-2 mm, membranous throughout, obtuse, strigulose or glabrous, erose or toothed, with lateral lobes, lobes less than 1.5 mm longer than the central portion; blades 1-6 cm long, 1-2 mm wide, flat to involute, smooth or scabridulous abaxially, hirsute adaxially, usually without necrotic spots. Panicles 4-13 cm long, 1-3(5) cm wide, not dense; primary branches 0.5-4 cm, appressed or diverging up to 30° from the rachises, spikelet-bearing to the base; pedicels 0.1-3 mm. Spikelets 3.5-5 mm. Glumes subequal, 2-4 mm, exceeded by the florets, 1-veined, scabrous on the veins and near the apices, apices acuminate, unawned or awned, awns to 1.2 mm; lemmas 3.5-5 mm, lanceolate, mostly purplish, veins conspicuously green, pubescent on the lower 1/3-1/2 of the midveins and margins, hairs to 1.5 mm, apices scabridulous, acuminate, awned, awns 4-12(20) mm, flexuous; paleas 3.5-5 mm, narrow-lanceolate, intercostal region pubescent, apices acuminate, veins sometimes extending into awns to 0.5 mm; anthers 1.3-3 mm, purple. Caryopses 2-2.3 mm, fusiform, brownish. 2n = unknown.

Muhlenbergia arsenei grows among granitic boulders, on rocky slopes, limestone rock outcrops, and in arroyos, at elevations of 1400-2850 m. Its range extends from the southwestern United States into Baja California, Mexico. It flowers from August to September.

The National Science Foundation
This project made possible by National Science Foundation Award 1410069