Plants perennial; dioecious, staminate and pistillate plants similar in gross morphology; rhizomatous. Sheaths overlapping, mostly glabrous or the young and bladeless leaves sparsely pilose, margins usually pilose distally; collars pilose in young leaves with rudimentary blades; ligules pilose; blades to 2 m, leathery, glabrous, lower blades disarticulating at maturity, midribs 0.5-1.5 cm wide, sometimes with a line of scattered hairs on either side. Panicles large, the pistillate panicles plumose. Pistillate spikelets with 2 florets; disarticulation above the glumes and between the florets; glumes 1-3-veined, tardily disarticulating; upper glumes longer and firmer than the lower glumes, exceeding the florets; lemmas shortly pilose below, long pilose above, apices elongated and narrowed; lodicules 2, membranous, faintly 2-3-veined, sometimes with long hairs, truncate; staminodes 2; styles 2. Staminate spikelets with 2-4 florets; disarticulation below the terminal florets; glumes 1-veined; lemmas hyaline, glabrous, occasionally puberulent below; lodicules2, free, faintly veined, truncate; anthers 2; ovary abortive. Name from the Greek gyne, woman, and erion, wool, a reference to the pistillate lemmas.