Japan Flora: Rhizomes long-creeping; culms 20-80 cm. long, erect; leaves somewhat flaccid; basal leaf-sheaths with blades, pale, partially brownish or purplish, the upper leaf-blades 1.5-4 mm. wide, soft, glaucous above, with slightly involute margins; staminate spikes solitary or sometimes 2, rarely 3, linear, 2-6 cm. long, the pistillate 2 or 3, long-cyl indr ic to oblong, 2-5 cm. long, erect, usually subsessile; pistillate scales oblong, dark reddish purple to purplish brown, paler toward the margins; perigynia 3-3.5 mm. long, oblong to elliptic, planoconvex, faintly nerved, pale green, obsoletely puncticulate, abruptly very short-beaked with an entire tip; stigmas 2, rather stout. May-June. Common in rice paddies and in swampy river flats;

Hokkaido, Honshu. Very polymorphic.

var. appendiculata (Trautv.) Ohwi. Rhi­zomes rarely creeping; culms densely tufted; leaves less soft.  May-July. Wet places, especially in bogs; Hokkaido, Honshu (Senjogahara in Nikko). Sakhalin, s. Kuriles, Kamchatka, Amur, Ussuri, and n. Korea.