Description from Flora of China
Rhizome shortly creeping. Culms 30-60 cm tall, trigonous, slender, ± scabrous above, rarely smooth, clothed at base with purple bladeless sheaths. Leaves shorter than culm, blades 2-3 mm wide, flat, slightly revolute, apex acuminate. Involucral bracts leaflike, longer than inflorescence, sheathless. Spikes 3-5, upper 3 approximate; terminal spike gynaecandrous, oblong, 6-8 mm; lateral spikes female, ovate or oblong-ovate, 4-5 mm; lowest spike with peduncle, upper subsessile. Female glumes ferruginous-brown, oblong-ovate, ca. 2 mm, 3-veined, margins narrowly white hyaline, apex acute. Utricles yellowish green, becoming yellowish brown, longer than glume, oblong-obovate or oblong-elliptic, ± inflated trigonous, 2.2-3 mm, thinly membranous, slender veined, base stipitate, apex abruptly contracted into a slightly curving beak, orifice emarginate, 2-toothed. Nutlets loosely enveloped, elliptic-obovate or elliptic, trigonous, ca. 2 mm, apex with a short beak; style slightly curving, base not thickened; stigmas 3. Fl. and fr. Jun-Aug.
Wet places in forests, grasslands at forest margins; 600-700 m. Heilongjiang, Jilin, Nei Mongol [N Mongolia, Russia (Far East, Siberia)].