Japan Flora: Perennial stoloniferous herb, the stolons slender, ending in a tuber; leaves long-petio- late, the blades sagittate, the basal lobes ovate to linear, the terminal lobe 5-15 cm. long, 3- to 7-nervcd, acuminate but with an obtuse tip, the lateral lobes ascending, usually longer than the midlobe, acuminate with a filiform tip; scapes 20-80 cm‘ long; racemes somedmes branched at base; flowers rather numerous, in 3’s at the nodes, the pistillate borne on the lower part, the sepals ovate, obtuse at apex, 6-8 mm. long, re­flexed, the pedicels 1-2 cm. long, the staminate longer pedi- celled; petals white, twice as large as the sepals; achenes broadly oblanceolate, 3-3.5 mm. long, obliquely obtriangular inclusive of the broad wing. June-Oct Wet places, paddy fields, riverbanks, and ponds.

Hokkaido, Honshu, Shikoku, Kyushu; common. Korea, China, and India.

var. edulis (Sieb.) Ohwi. Tubers at apex of stolons larger; leaves with broadly ovate midlobe. Introduced from China and frequently cultivated in Japan for the edible tubers.

var. alismifolia (Makino) Makino. Leaves entire, linear to narrowly oblong, 4_6 cm. long, 4-18 mm. wide. Nov. s. Kyushu.