Japan Flora: Rhizomatous; culms terete, 30-60 cm. tall, 1.5-3 mm. thick; spikelets narrowly to broadly ovate, rarely broadly lanceolate, 7-15 mm. long, 3-5 mm. wide; scales narrowly ovate, 3-4 mm. long, dark purplish red, subacute to obtuse; achenes tawny, obovate or broadly so, 1.2-1.7 mm. long, turgid-biconvex, the style base deltoid, 1/3 to 1/2 as wide as the achene, the bristles 4, slender, ferrugineous, retrorsely scabrous, longer than the style base, more or less flexuous. JuIy-Oct. Marshy places and shallow ponds in mountains.

Hokkaido, Honshu (n. distr.). Sakhalin, Kuriles, Man­churia, and e. Siberia