Plants cespitose, sometimes rhizomatous. Culms 3–26 cm, erect to ascending; nodes 2–3. Ligules (0.2)0.5–4 mm, smooth, truncate, rounded or acute, usually entire or erose; blades 1.5–4(5) cm long, 0.4–1.5 mm wide, flat or folded; flag blades usually below, sometimes near midculm. Panicles 1.5–6 cm long, 0.2–0.7(1.5) cm wide, sometimes wider at anthesis, linear to narrowly oblong, lowest node with 1–3(4) branches; branchessmooth, usually appressed to erect, ascending at anthesis, branching in the distal 1/3–3/4; lower branches0.5–1.5 cm; pedicels 0.4–1.5 mm. Spikelets usually purplish; rachilla prolongations 0.1–0.6 mm, glabrous or bristlelike, with a tuft of short hairs at the apex. Glumes subequal, 1.6–2 mm, exceeding the lemma by 0.2–0.4 mm, ovate to elliptical, 1-veined or 3-veined at base, veins smooth or scabridulous distally, apices acute; calluses glabrous or sparsely hairy, hairs to 0.5 mm; lemmas 1.5–2 mm, usually purplish, smooth, opaque, 5-veined, veins obscure or prominent distally, apices acute, entire or erose, rarely awned, awns to about 1.3 mm, usu subapical, smt attached near midlength, lemma veins occasionally excurrent to 0.4 mm; paleas 0.9–1.6 mm; anthers 3, 0.4–1mm. Caryopses 1–1.3 mm. 2n = 14.
Podagrostis humilis is a western North American species that grows in undisturbed alpine and subalpine meadows and screes at over 3500 m, down to meadows, fens, and open woodlands at less than 200 m. It usually differs from P. thurberiana in overall size and in having narrower, more basally concentrated leaves. In the field, dwarf forms of P. humilis mimic Agrostis variabilis; they differ from that species in having paleas.