Description from Flora of China
Perennials. Rhizomes very short, with dense and slender fibrous roots. Culms tufted, erect, 20-40(-60) cm tall, 0.5-1 mm thick, 3-angled, basally clothed with pale yellowish bladeless sheaths, apically sometimes slightly scabrous. Leaves basal and a few cauline, shorter than culm; leaf blade filiform, 0.5-1 mm wide, 3-angled, sometimes slightly scabrous, apex finely acuminate. Involucral bracts leaflike or setaceous, sheathing. Inflorescences paniculate, consisting of a terminal and 3 or 4 lateral corymbiform anthelae; anthelae small, very distant, with 2-5 spikelets. Spikelets erect, dark brown, narrowly ovoid, ca. 3.5 mm, base subtruncate, apex acuminate. Glumes 5 or 6, ovate to elliptic-ovate, 1- or 2-flowered; basal 3 or 4 glumes narrowly ovate, empty. Perianth bristles 6, slightly longer than nutlet, retrorsely scabrous. Stamen 1; filament as long as nutlet and style base. Style slender; stigmas 2. Nutlet brown to pale reddish brown, broadly obovoid to obovoid-globose, 1.5-2 mm, biconvex, finely transversely wrinkled with longitudinally oblong epidermal cells; persistent style base narrowly conic, 1/3-2/3 as long as nutlet. Fl. and fr. Aug-Oct.
Swamps, stream margins; ca. 400 m. Fujian, Guangdong, Guangxi, Hunan, Jiangsu, Jiangxi, Shandong, Zhejiang [Japan, Korea, Russia (Far East)].