How does pollination occur in underwater plants? Please explain.

Many aquatic plants bear their flowers above the surface of water and are pollinated by wind or insects.

Aquatic plants sometimes may fertilize through Hydrophily. It is the mode of pollination involving the transfer of pollen grains through water. But it does not occur in all aquatic plants.

It is of two types:

1. Hypo hydrophily:The pollen grains float below the surface of water, and on reaching the stigma, coil around it and germinate. Example: Zostera marina.
2. Epi hydrophily:It takes place over the surface of water in plants. After maturity, the male flowers will get detached from parent plant and start floating on the water surface. When the female flowers raise itself up to water surface the male flower surrounds it and pollination occurs. Example:  Vallisneria.