Japan Flora: Soft spongy greenish herb with slender rhizomes; stems erect, 0.7-1 m. long, rather stout; leaves flattened, keeled on back, linear, elongate, 7-12 mm. wide, slightly narrowed upward to an obtuse apex; panicle 30-50 cm. long, the bracts leafy, the lower ones sometimes exceeding the panicle, the branches few, each with 1-3 pistillate heads in lower part and several staminate heads loosely disposed above; pistillate flowers sessile; style elongate, the sdgma filiform; fruit rounded-obovoid, angular, 6-10 mm. long, 4-8 mm. in diame­ter, sessile. June-Aug. Shallow water in lowlands.

Hok­kaido, Honshu, Shikoku, Kyushu. Korea, China to Turkes­tan, and Afghanistan.