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Perennial or annual aquatic and marsh herbs. Leaves floating; leaf-blade broadly elliptic to broadly ovate; apex rounded to obtuse; base truncate to deeply cordate. Peduncle longer than the leaves; inflorescence compound, pyramidal, consisting of whorls of 3 branches or 3 flowers subtended by 3 lanceolate bracts, and 2 or 3 smaller bracteoles. Flowers bisexual. Sepals 3, spreading or reflexed. Petals 3, white. Stamens 6(–11); filaments filiform or flattened; anthers oblong. Carpels 2–9(–20), free, crowded on a small receptacle; style ventral; ovules solitary, basal. Achenes swollen, smooth, ridged or warty; style persistent, ventral.
Herbs, aquatic, perennial, rhizomatous. Leaves all basal, aerial, floating, or submerged, ovate to elliptic; floating leaves deep green, large; aerial leaves subleathery, with erect petiole; submerged leaves usually smaller. Inflorescences paniculate or racemose, much branched; branches whorled, each whorl with 3-6 branches; bracts lanceolate. Flowers pedicellate, verticillate, bisexual. Petals usually larger than sepals. Stamens 6-12. Carpels few to numerous in a single whorl, free, each with 1 ovule. Fruitlets drupaceous, with woody endocarp and spongy exocarp, swollen or slightly compressed, with a short beak.
Leaves broad-elliptic to broad-ovate, apex blunt, base cordate (rarely truncate outside Mal.). Panicle pyramidal; branches and pedicels on the branches in whorls of 3, each branch and each pedicel sustained by an oblong-lanceolate bract. Flowers bisexual. Petals white. Stamens 6(-11); filaments filiform. Carpels 2-9(-20) crowded, not in a whorl; style ventrally inserted, slender; achene swollen, without lateral air-chambers; endocarp formed by large, radially arranged sclerenchymatic cells (colouring red with phloroglucin); exocarp spongy or membranous. Seed oblong.
The flowers have both sexes. There are 6 stamens.
