Japan Flora: Annual; stems 10-50 cm. long, sometimes short-creeping at base, usually branched in upper half, glabrous or short-pubescent fruit; filaments loosely short-pilose on lower half; nutlets about 0.7 mm. long, pale brown, ovate, narrowed at base. Aug.-Oct. Wet places;
Honshu, Shikoku, Kyushu. Korea, Ryukyus, Formosa, China, and se. Asia.