Habit: aquatic herbs from an underwater rhizome, no vessels
Leaves: alternate, large, simple, long-petiolate, floating or emersed, estipulate, peltate
Inflorescence: long peduncled solitary flowers
Sepals: 4-many, distinct or basally connate
Petals: 8-many, distinct or basally connate
Stamens: numerous, spirally arranged, distinct or basally connate, filaments flattened and often petaloid
Ovary: carpels 5-many, connate, style absent, stigmas distinct, ovary superior to inferior with 5-many locules and numerous laminar ovules.