Japan Flora: Culms few, 20-50 cm. long; leaf­blades flat, rather firm, light green, 4-8 mm. wide, the basal sheaths pale, with short blades; spikes 3(2-4), the terminal staminate, erect, long-pedunculate, linear, 2-3 cm. long, stramineous-green, the others pistillate, ellipsoidal to nearly globose, densely flowered, 15-20 mm. long, about 15 mm. wide, closely approximate, subsessile, the bracts leaflike, spread­ing to reflexed; pistillate scales broadly ovate, tawny or pale; perigynia much longer than the scales, about 10 mm. long, spreading to divergent, broadly ovoid-conical, strongly in­flated, lustrous, bright green, nerved, abruptly long-beaked, the beak slender, acutely 2-toothed at tip; stigmas 3.            May-July. Shallow water in ditches and edges of ponds.

Hok­kaido, Honshu, Shikoku, Kyushu; rather common. Korea.