Japan Flora: Minutely pilose papillose annual; stems slender, scandent, 40-100 cm. long; leaves sagittate-cordate, 3-4.5 cm. long, 25-4.5 cm. wide, acute to acuminate, cordate at the base, the petioles 1-5 cm. long; sheaths obliquely truncate, 2-5 mm. long; flowers in loose terminal panicles and in small axillary fascicles, greenish, about 3.5 mm. long in fruit, wingless; achenes ovoid, dull, punctulate, enclosed in the perianth, acutely trigonous, about 3mm. long. June-Sept.

Naturalized; Hokkaido, Honshu, Kyushu. Eurasia.