Japan Flora: Stems slender, elongate, 1- to 2-leaved; leaves ovate-cordate or orbicular-cordate, 2-6 cm. across, deeply 2-lobed, entire, the petioles decurrent on the stem, unequal in length, 1-10 cm. long, auriculate; flowers few, white, about 8 mm. across, fasciculate, the pedicels 1-3 cm. long; calyx-lobes broadly lanceolate, subacute, 3-4 mm. long, membranous; corolla-lobes ciliate; capsules ellipsoidal, 4-5 mm. long, slightly longer than the calyx; style a little less than 1 mm. long. Aug. Ponds and shallow water.

Honshu, Shikoku, Kyushu. Korea and Ryukyus