Japan Flora: Rhi­zomes elongate, terminated by an oblong tuber; culms 50-100 cm. long, s的ut, usually smooth; leaves 5-8 mm. wide; corymbs compound, large, with 5-8 erect-spreading smooth rays, subtended by 3 or 4 spreading leaflike bracts; spikes 2-4 cm. long and as broad, the rachis usually appressed-setulose; spikelets 1-2 cm. long, 2-25 mm. wide, turgid-biconvex, dark sanguineous to pale green; scales broadly ovate, 2-2.5 mm. long, obtuse, not keeled, entire, involute; achenes 1.5 mm. long, nearly orbicular, biconvex, dorsiventrally compressed. brownish; stigmas 2, rarely 3. Aug.-Oct. Marshy places. 

Hokkaido, Honshu, Shikoku, Kyushu. Korea, Manchuria, Formosa, China, India, and Europe.