Heterophyllous

Heterophyllous: Having leaves of different shapes on the same plant.
Heterostylic: Having flowers which differ in the relative length of their styles and stamens, such that any one flower is very rarely, if ever, self pollinated.

Myriophyllum triphyllum (left), and M. propinquum (right) with heterophyllous leaf forms (smaller emergent leaves at tips, and larger feathery submersed leaves).
Potamogeton ochreatus ...

See also: Aquarium, Temperature, Gravel, Plants, Water