Japan Flora: Rhizomes slender, creeping; steins erect, 30-50 cm, long, many-leaved, rather soft, glabrous or slightly pubes­cent on the nodes, usually simple; inflorescence terminal, spi­cate; leaves usually verticillate in 4，s, linear or broadly linear. 3-7 cm. long, 2-5 mm. wide, obtuse，narrowed at both ends, entire, glabrous on both sides or loosely short-pubescent on midrib above, nearly sessile; spikes 2-8 cm. long, densely very many-flowered; flowers nearly sessile, rose-colored, 7-8 mm. long inclusive of the long exserted stamens, the bracts lanceo­late, as long as the calyx, pubescent; calyx about 3 mm. long. pubescent; filaments with a dense tuft of long crisped hairs near middle; nutlets ovate, biconvex, about 0.7 mm. long, ob­tusely angled, narrowed below and subtruncate at base.  Aug.-Oct. Wet places;

Honshu, Shikoku, Kyushu. Korea.