aquatic rhizomatous herbs. Leaves arising from rhizome, simple, long-petioled,
leaf blade cordate or hastate to peltate, usually floating. Flowers solitary,
large and showy, bisexual, regular, hypogynous to epigynous. Sepals 4-6, free.
Petals 8 to many, usually passing into the stamens. Stamens many, spirally
arranged, mostly laminar and 3-nerved, filaments flat and free. Carpels many
(3-35), stigmas usually radiating. Fruits spongy, berry-like.