Rhizome short. Culms 40-70 cm tall, 1.5-2 mm thick, trigonous, scabrous above, clothed at base with light brown bladeless sheaths. Leaves shorter than culm, blades linear, 2-3 mm wide, flat, margins scabrous. Basal involucral bracts leaflike, shorter than inflorescence, sheathless, remaining bracts setaceous. Spikes 3-5; terminal spike male, occasionally some becoming androgynous bearing several male flowers at apex, cylindric, 20-40 × 4-5 mm, densely many flowered, subsessile. Female glumes blackish purple, oblong or ovate-lanceolate, 3.5-4 × 0.8-1 mm, with light midrib, apex acuminate. Utricles blackish purple, lower part light brown, shorter than glume, oblong, ca. 3 × 1.2 mm, base very shortly stipitate, apex gradually narrowed to a short beak ca. 0.3 mm, orifice entire. Nutlets yellow-brown, slightly loosely enveloped, obovate, ca. 1.5 × 1 mm; style base not thickened; stigmas 2. Fl. and fr. Jul-Aug.