Perennials, stoloniferous. Rhizomes woody, covered with brown scales. Culms laxly tufted to scattered, 70-110 cm tall, 3-4 mm wide, 3-angled, slightly puberulent. Sheath brown to greenish brown at middle part of culm, 1-6 cm, papery, puberulent, wings 1-3 mm wide; contraligules nearly semicircular, puberulent, barbate; leaf blade linear, to 35 cm × 3-8 mm, both surfaces pubescent. Involucral bracts leaflike, sheathing; bractlets setaceous, puberulent, base auriculate. Inflorescences paniculate, with 2-4 lateral branches; branches 2-7 × 1.5-5 cm, slightly distant. Spikelets 1 or 2 in a cluster, greenish purple to dark purple, 3.5-4.5 mm, unisexual. Male spikelets narrowly ovoid; basal glumes 1.5-3.3 mm, thickly membranous; apical glumes thinner and paler. Female spikelets usually at basal part of branch, narrowly ovoid; glumes 5; basal 2 glumes ovate, not keeled; apical 3 glumes ovate to ovate-lanceolate, keeled, apex awned. Male flowers: stamens 3. Female flowers: stigmas 3. Disk yellowish white, slightly narrower than nutlet, deeply 3-lobed, margins partly reflexed. Nutlet white, spherical, 2.5-2.8 mm in diam., 3-sided, reticulate, puberulent, apex tipped. Fl. and fr. Jul-Sep.