Potamogetonaceae

Aquatic perennials or annuals. Stems floating or creeping. Leaves simple, opposite or alternate. Inflorescence a spike; flowers regular, bisexual, perianth absent or 4, sepaloid appendages present. Stamens 2–4. Ovary superior, carpels 2–19. Fruit nut-like or drupe-like. 3 gen., cosmop., fresh water herbs.