Plants perennial; forming small, dense tufts. Culms 5-30 cm. Sheaths generally shorter than the internodes; ligules 1-1.5 mm, ciliate; blades 1-1.5 mm wide, flat or folded, with thick, scabrous, white margins; cauline blades 1-2.5 cm; innovation blades to 6 cm. Panicle brances 6-15 cml rachises ciliate. Spikelets 2.5-3.5 mm; lemmas 2-2.5 mm, keel spilose, margins densely pilose, hairs 0.2-1 mm. 2n = 24, 40.
Microchloa kunthii grows on granitic outcrops on rocky slopes. Its range extends southward from Carr Canyon, Huachuca Mountains, Arizona and the Big Bend region of Texas through Mexico to Guatemala.