Japan Flora: Rhizomes stout, creeping; leaves radical, the submersed ones narrow, membranous, with undulate margin, die aerial ones subcoriaceous, narrowly ovate to oblong, 20-30 cm. long, 7-12 cm. wide, obtuse to rounded, sagittate, glabrous above, slighdy pubescent beneadi while young, entire; peduncles raised above the water; flowers yellow, 4-5 cm. across; sepals obovate-orbicular, about 2.5 cm. long, subcoriaceous, becoming green in fruit, rounded at apex; petals obovate-cuneate, about 8 mm. long; anthers 4-6 mm. long; stigma-disc 6-8 mm. across, dentate. June-Sept. Ponds, lakes, and shallow streams 

Hokkaido (sw. distr.), Honshu, Shikoku, Kyushu; common.

var. rubrotinctum (Casp.) Ohwi. Flowers orange-red. Known only in cultivation.