In Myriophyllum, asexual mode of reproduction is by vegetative reproduction. The leaves of Myriophyllum are very large. They have margins that help in the process of vegetative propagation. They develop buds from their margins. These buds develop from notches over their margins. These are called epiphyllous buds. These buds develop into new individuals.
So, leaves help in vegetative reproduction of Myriophyllum.