Perennials. Rhizomes hardened. Culms 1-2.5 m, 4-10 mm thick, triquetrous, scabrous on apical angles. Leaves ± in whorls of 2-5 at mid-culm (otherwise scattered); sheaths 4-6 cm, papery, glabrous, winged or not; contraligule depressed rounded, margin ciliate; leaf blade linear, ca. 40 × 1-1.3 cm, thickly papery, slightly scabrous, apically attenuate. Involucral bracts leaflike, basalmost to 15 cm, sheathing; bractlets setaceous. Inflorescences paniculate, with several branches; lateral branches spreading, often 2 or 3 in a cluster, 6-7 × ca. 10 cm, axes angled. Spikelets 2 or 3 in a cluster, brown, 3-4 mm, unisexual. Male spikelets oblong-ovoid, pedicellate, apex truncate; glumes rust-colored to brown, 3-4 mm, membranous, basal ones keeled and with a cuspidate apex. Female spikelets narrowly ovoid, apex acuminate; glumes broadly ovate to ovate, keeled. Male flowers: stamens 3; anthers linear, ca. 1 mm; connective apex protruding, ca. 1/4 as long as anther. Female flowers: stigmas 3. Disk brown to purple, 3-lobed; lobes smooth, narrow, apex acute. Nutlet whitish, globose, 2.5-3 × 2.2-2.7 mm, slightly 3-sided, with hexagonal reticulation, scrobiculate (marked with many shallow depressions, grooves, or pits), glabrous but sparsely pubescent on ridges, apex cuspidate. Fl. and fr. Apr-Aug.