Japan Flora: Glabrous annual; roots fi­brous, purplish; culms simple or branching at base, 5 to 20 cm. long, several-leaved; leaves flat, short, broadly linear, 15-25 mm. long, 2-3 mm. wide, rather abruptly pointed at apex, the sheaths 3-10 mm. long; partial inflorescences several, capitate, axillary, short-peduncled, 3-5 mm. across, light green; pistillate 8-nerved, 3-toothed at apex, the central tooth longer than the others; achenes scarcely 1 mm. long, globose, indistinctly 3-ribbed, coarsely reticulate, more or less puberulent on the net. July-Oct. Wet places. 

Honshu (Kadzusa Prov. and westw.), Shikoku, Kyushu; rare Ryukyus, Formosa to India, and Australia.