Rhizome short, long stoloniferous. Culms 40-70 cm tall, trigonous, scabrous above, clothed at base with yellow-brown sheaths disintegrating into reticulate fibers. Leaves subequaling culm, blades linear, 3-6 mm wide, flat, margins scabrous. Involucral bracts leaflike, lowest one surpassing inflorescence, sheathless. Spikes 3-6; terminal spike male, cylindric, 20-40 × ca. 4 mm, with peduncle 0.8-2 cm; lateral spikes female, cylindric, erect, 10-45 × ca. 6 mm, often sessile, only lowest one with short peduncle. Female glumes light brown, narrowly lanceolate or narrowly oblong, 2-3 mm, green 1-3-veined costa excurrent into a mucro. Utricles light brown, slightly longer than glume, obovate or elliptic, compressed biconvex, 2.5-3 mm, densely minutely papillose, base truncate, apex abruptly contracted into a beak ca. 0.5 mm, orifice 2-toothed. Nutlets dark brown, tightly enveloped, broadly obovoid or obovoid, 2-2.2 mm; style base not thickened; stigmas 2. Fl. and fr. Apr-Jul.

Marshes, watersides; 500-1900 m. Hebei, Heilongjiang, Hubei, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi [Japan, Korea].