Rhizome short, indurate. Culms tufted, 10-70 cm tall, trigonous, scabrous above, clothed with brown bladeless sheaths at base. Leaves shorter than culm, blades linear, 1-2 mm wide, flat or plicate, apex acuminate; membranous side of leaf sheaths not transversely wrinkled, with purple-red spots. Lower involucral bracts 1 or 2 leaflike, green, much surpassing inflorescence, upper involucral bracts setaceous. Spicate inflorescence long cylindric, 2.5-50 × 0.7-1 cm, dense at apex, lower ones distant; spikes numerous, androgynous, ovate 5-9 × 4-6 mm, sometimes spikes branched at base. Female glumes pale green, ovate, 2.5-2.8 mm, membranous, green 1-veined, apex acute, awned. Utricles pale green, rarely tinged with red-brown, longer than glume, ovate-lanceolate or oblong-elliptic, plano-convex, 2.5-3.5 × ca. 1 mm, membranous, many veined on both faces, glabrous, base shortly stipitate, margins thickened, without wings, apex gradually narrowed into a long beak, orifice 2-toothed. Nutlets pale brown, tightly enveloped, broadly elliptic or suborbicular, plano-convex, ca. 1.2 mm, base shortly stipitate; stigmas 2. Fl. and fr. Jun-Aug.

Streamsides, forest margins and roadsides on slopes, grassy slopes, wet places; (1100-)1300-3700 m. Chongqing, Gansu, Guizhou, Hubei, Ningxia, Shaanxi, Sichuan, Taiwan, Xizang, Yunnan [?Afghanistan, Bhutan, India, Indonesia (Java), Japan, Malaysia, Nepal, ?Pakistan, Philippines, Russia (Kuril Islands), Sri Lanka, Vietnam].