Rhizome short, densely caespitose. Culms tufted, 20-50 cm tall, 1-1.5 mm wide, slender, obscurely trigonous, rigid, smooth, clothed at base with chestnut-brown lustrous bladeless sheaths disintegrating into fibers. Leaves shorter than or subequaling culm, blades setaceous, flexuose, rather stiff, folded, margins scabrous. Involucral bracts sheathless, lowest one setaceous, upper ones glumelike. Spikes 2 or 3, approximate; terminal spike male, cylindric, 1.5-2 cm; lateral spikes female, globose or ovate, 5-12 × ca. 0.5 mm, densely flowered. Female glumes dark purple or red-brown, ovate-oblong, 2.8-3.5 mm, faintly 3-veined, margins narrowly white hyaline, apex obtuse. Utricles bluish green to gray, equaling or nearly longer than glume, ovate or elliptic, compressed trigonous, 2.5-3 mm, finely 5- or 6-veined, densely papillose, base shortly stipitate, apex abruptly contracted into a cylindric entire beak. Nutlets brown, tightly enveloped, obovate-elliptic, compressed trigonous, 1.5-2 mm, base shortly stipitate, apex rounded; style base not thickened; stigmas 3. Fl. and fr. Jun-Jul.

Marshes. Heilongjiang, Jilin, Liaoning, Nei Mongol, Sichuan [Japan, Korea, Mongolia, Russia (Far East, Siberia)].