Japan Flora: Rhizomes stout; floating leaves broadly ovate to ovate-orbicular, 5-8 cm. long, 4-6 cm. wide, rounded, deeply cordate-sagittate
at base, entire, the petioles flattened, slightly hollow; flowers yellow, 3-4 cm. across; sepals obovate, about 2 cm. long; petals
broadly spathulate, about 6 mm. long, shallowly refuse; anthers 2-2.5 mm. long, oblong; stigma-disc 6-7 mm. across, shallowly
dentate. July. Ponds and shallow lakes;

Honshu (w. distr. and westw.), Kyushu.