Herbs, aquatic or of marshes. Leaves aerial, floating, or submerged, all radical, erect, long petiolate, ovate to ovate-elliptic. Flowers usually solitary or up to 3 at apex of scape, bisexual, pedicellate. Petals usually larger than or ca. as large as sepals. Stamens 9. Carpels numerous in a subglobose head, free, spirally arranged, each with 1 ovule; style erect. Fruitlets achenelike. Achenes laterally compressed, with a long stylar beak.

About two species: Asia, also tropical and subtropical regions of Africa; one species in China.