Hydrophily

Main article: Pollination syndrome

Hydrophily is a fairly uncommon form of pollination whereby pollen is distributed by the flow of waters, particularly in rivers and streams. Hydrophilous species fall into two categories: those that distribute their pollen to the surface of water, and those that distribute it beneath the surface.

Surface pollination is rare, and appears to be a transitional phase between wind pollination and true hydrophily. Surface hydrophily has been observed in several species of Potamogeton as well as some marine species.

Species exhibiting true submerged hydrophily include Posidonia australis and Zostera marina.