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.
Stamens (6–)9(–12); filaments filiform
Carpels ∞, free on a convex receptacle; styles terminal, hooked; ovules solitary, basal
Fruit a globose head of achenes spirally arranged on the elongated receptacle; achenes strongly compressed laterally, glandular, winged, with a terminal beak formed by the remains of the style.
Perennial stoloniferous glabrous marsh herbs
Inflorescence pseudo-umbellate, 1–3-flowered with 2 membranous bracts; flowers sometimes replaced by vegetative buds—the peduncle bends over stolon-like and the buds develop into new plants
Leaves erect, or spreading; leaf-blade ovate to linear-lanceolate; base cordate to cuneate
Sepals 3, reflexed in the fruiting stage