Japan Flora: Rhizomes abbreviated; culms 20-60 cm. long, slender, smooth, very loosely few-leaved; leaves 1.5-2.5 mm. wide; corymbs 2 or 3, the branches short; spikelets broadly lanceolate, 7-8 mm. long, dark reddish brown; achenes broadly obovate, glabrous, 2 mm. long, faintly transversely wrinkled, the beak slightly shorter than the achene, deltoid, glabrous; bristles 6, slender, 3-4 times as long as the achene, retrorsely scabrous.  July-Oct. Wet places. 

Wet places in low­lands; Hokkaido, Honshu, Shikoku, Kyushu; common. Korea, China, and Ussuri