Rhizome short. Culms densely tufted, 30-80 cm tall, slender, trigonous, scabrous, clothed at base with castaneous-brown bladeless sheaths slightly disintegrating into reticulate fibers. Leaves shorter than culm, blades 2-3 mm wide, flat, margins revolute. Lowest involucral bract leaflike, subequaling inflorescence, sheathless. Spikes 3-5; upper 1-3 spikes male, approximate, linear or narrowly cylindric, 1-3 cm; remaining spikes female, cylindric, 12-30 × 4-6 mm, lower spikes with short peduncles, upper subsessile. Female glumes castaneous-brown, lanceolate, ca. 3 mm, margins narrowly white hyaline, 3-veined costa excurrent into a mucro, apex acute. Utricles brown-green or castaneous-brown, slightly shorter than or equaling glume and 2 × as broad as glume, broadly obovate or suborbicular, inflated, 2-3 mm, densely minutely papillose, nerveless except for 2 marginal veins, base shortly stipitate, upper margins slightly scabrous, rarely smooth, apex abruptly contracted into a short beak, orifice entire. Nutlets brown, tightly enveloped, obovate-orbicular, biconvex, ca. 1.8 mm wide; style base not thickened; stigmas 2. Fl. and fr. Jun-Jul.

Marshes, streamsides, forest margins. Heilongjiang, Jilin, Nei Mongol [Japan, Korea, Mongolia, Russia (Far East, E Siberia)].