Description from Flora of China
Rhizome short, stout, indurate. Culms tufted, 25-50 cm tall, slender, trigonous, smooth, clothed at base with brown or pale brown bladeless sheaths disintegrating into fibers. Leaves shorter or longer than culm, blades linear, 2-3 mm wide, flat, soft; membranous side of leaf sheaths at mouth projected forming a tonguelike appendage or not. Lower involucral bracts leaflike, surpassing inflorescence. Spikes 5-10, gynaecandrous, oblong, 5-15 × 3-4 mm, upper spikes approximate, lower ones remote. Female glumes pale, oblong, 2.5-3 mm, green 3-veined costa excurrent into a scabrous short awn, apex acute. Utricles green or green-yellow, longer than glume, lanceolate or ovate-lanceolate, 3-4 mm, conspicuously veined on both faces, many veined abaxially and hardly veined adaxially, or nerveless, base cuneate, shortly stipitate, upper half of margins narrowly scabrous winged, apex gradually attenuate into a long beak, orifice 2-toothed. Nutlets tightly enveloped, plano-convex, 1.5-2 mm, base contracted and shortly stipitate, apex subrounded; style base thickened; stigmas 2. Fl. and fr. May-Aug.
Forests, wet grasslands, swamps, grasslands and thickets at high elevations. Anhui, Gansu, Guangxi, Guizhou, Henan, Hubei, Hunan, Jiangsu, Shaanxi, Shanxi, Sichuan, Taiwan, Yunnan, Zhejiang [Bhutan, India, Indonesia, Japan, Nepal, Sri Lanka].