Rhizome shortly stoloniferous. Culms 50-70 cm tall, trigonous, smooth, clothed at base with pale brown sheaths disintegrating into fibers. Leaves linear, ca. 1/3 length of culm, blades pale green, 3-5 mm wide, flat, firm, upper margins scabrous, apex acuminate. Involucral bracts leaflike, shorter than inflorescence, sheathing. Spikes 3-5; upper 1 or 2 spikes male, oblong, 10-15 × 3-4 mm; remaining spikes female, elliptic or oblong, 10-17 × 5-10 mm, densely many flowered, with slender, smooth peduncles 2-4 cm. Female glumes pale ferruginous below, purple-brownish above, ovate, ovate-oblong, or ovate-lanceolate, 4-4.2 × ca. 2 mm, with a green midrib, margins narrowly white hyaline, apex acute or acuminate. Utricles yellowish brown, longer than glume, broadly elliptic, much compressed trigonous, 4.8-5.2 × ca. 3 mm, glabrous, faintly veined, base and apex subrounded, margins pale green, sometimes upper margins minutely dentate, apex abruptly contracted into a short, narrowly cylindric beak, orifice pale hyaline, 2-toothed. Nutlets yellowish, very loosely enveloped, ca. 1.5 mm, base with a stipe ca. 1 mm; style slender, erect, base not thickened; stigmas 3. Fl. and fr. Jun-Aug.

Wet grasslands on riverbanks, boggy meadows, slopes, marshes; 700-3500 m. Gansu, Hebei, Heilongjiang, Nei Mongol, Qinghai, Shanxi [Mongolia, Russia (Siberia)].