Plants often densely cespitose, densely and softly pubescent throughout, with soft, thin, spreading, papillose-based hairs on the culms and lower sheaths. Culms usually over 30 cm. Midculm sheaths about 1/2 as long as the internodes; blades at midculm generally 6.5-12 cm long, usually more than 7 times as long as wide, suberect, softly pubescent on the abaxial surface, without papillose-based cilia on the distal 1/2. Primary panicles usually poorly exserted, peduncles shorter than 6 cm. Spikelets mostly 1.8-2 mm.
Dichanthelium acuminatum subsp. thermale grows on the mineralized crust of warm, moist soil at the Geysers, Sonoma County, California; it is listed as endangered in that state.