Japan Flora: Rhizomes short-creeping; culms tufted, slender, 50-80 cm. long, obtusely angled, scabrous above; leaf­blades flat, 2-2.5 mm. wide, scabrous on the margins; inflores­cence ovate to oblong, 2-3.5 cm. long, ebracteate; spikes numerous, crowded, androgynous, ovoid-globose, 5-7 mm. long; pistillate scales oval, acute, castaneous, with whitish, somewhat translucent margins; perigynia coriaceous, lustrous, longer than the scales, broadly ovoid, 3 mm. long, spreading, dark chestnut-brown at maturity, thick-biconvex, indistinedy 3- to 5-nerved at base, obtusely margined, stipitate, abrupdy beaked, the beak moderately long, setulose-scabrous on mar­gins, the tip almost entire; style bifid. June-July. Swamps. 

Hokkaido, Honshu (Shimokita Penin, in Mutsu and Izunano- hara in Shinano Prov.); rather rare. Sakhalin, s. Kuriles, and widely dispersed in the cooler regions of the N. Hemi­sphere.