Description from Flora of China
Rhizome creeping. Culms 20-50 cm tall, slender, trigonous, scabrous, clothed at base with reddish brown to castaneous sheaths usually disintegrating into fibers. Leaves shorter than culm, blades linear, 2-3 mm wide, flat, margins scabrous. Lowest involucral bract setaceous, shorter than inflorescence, sheathless, upper ones glumelike. Spikes 2-4, distant; terminal spike male, cylindric, 2-3.5 cm, with peduncle 1.5-2 cm; lateral spikes female, cylindric or oblong, (10-)17-30 × 4-6 mm, densely many flowered, lower peduncles 10-18 mm. Female glumes dark brown, narrowly oblong, ca. 2.5 × 0.7-0.9 mm, with light midrib, margins narrowly white hyaline, apex obtuse or acute. Utricles brownish green to ferruginous-green, slightly longer than glume and 2-3 × as broad, broadly ovate or obovate, plano-convex, ca. 2.5 × 1.8 mm, densely minutely papillose, faintly veined, base shortly stipitate, apex with cylindric short beak, orifice weakly emarginate. Nutlets brown, obovate, ca. 2 mm; style base not thickened; stigmas 2. Fl. and fr. Apr-Jul.
Marshes, riversides, moist places; 100-3300 m. Gansu, Ningxia, Qinghai, Xinjiang [Russia].