Japan Flora: Sterile culms ultimately leafy, much elongated, decumbent, bearing scapes from the nodes the following year; fertile culms solid, 20-40 cm. long, acutely angled, slightly scabrous above; leaf­blades flaccid, 2-4 mm. wide; inflorescence oblong-cylindric, 15-30 mm. long, ebracteate, the 5-8 loosely aggregated spikes androgynous (or unisexual), ovoid, 5-10 mm. long, light castaneous; perigynia ovate-elliptic, slightly longer than the ovate, acutely pointed scales, compressed, more or less spongy toward the narrowly-winged margins, scabrous at tip, short- beaked; style bifid. June-July. Swamps.

Hokkaido, Hon­shu (Mutsu, Yechigo). s. Kuriles, Sakhalin, Korea, and Ussuri