Plants perennial; usually cespitose, occasionally stoloniferous. Culms 6-65 cm, erect. Leaves mostly basal; sheaths smooth, glabrous, striate, margins hyaline, collars with tufts of 1-3 mm hairs; blades usually folded, pilose basally, margins white, cartilaginous, apices acute but not sharp. Inflorescences terminal, simple panicles (racemes in depauperate specimens), exserted well above the leaves. Spikelets laterally compressed, with 3-20 florets, distal florets staminate or sterile; disarticulation above the glumes and between the florets. Glumes thin, membranous, 1-veined, acute to acuminate; calluses with hairs; lemmas rounded on the back, 3-veined, veins conspicuously pilose, at least basally, apices toothed or obtusely 2-lobed, midveins often extended into awns, awns to 4 mm, lateral veins sometimes extended as small mucros; paleas shorter than the lemmas, keels ciliate, intercostal regions pilose basally; lodicules 2, adnate to the bases of the paleas; anthers 1 or 3. Caryopses glossy, translucent; embryos more than 1/2 as long as the caryopses. x = 8. Name from the Greek erion, wool, and neuron, nerve, a reference to the hairy veins of the lemmas.