Hypohydrophily

Hypohydrophily is a form of hydrophily, the pollination of aquatic flowering plants by water, in which pollen transfer occurs entirely underwater. In this mode, both the pollen-producing structures (anthers) and the receptive structures (stigmas) are submerged, and pollen grains are released into the water and carried by currents to compatible stigmas. Hypohydrophily is one of several strategies aquatic plants use to achieve fertilization in an aquatic environment; it contrasts with epihydrophily, where pollination occurs near or at the water surface, and with other pollination modes such as wind or animal-mediated pollination.

Mechanism and traits commonly associated with hypohydrophily include submerged flowers and stigmas that are exposed to the water column. Pollen grains tend to be small and buoyant or otherwise suited to movement in water, often lacking adhesive properties typical of terrestrial pollen. Successful pollination relies on the alignment of flowering times with water movement and on the presence of receptive stigmas in the same water layer as the pollen, allowing transfer without contact with air or pollinators.

Distribution and examples are mainly among aquatic angiosperms. Hypohydrophily has been documented in certain pondweeds (Potamogeton spp.) and related aquatic taxa, as well as in some seagrasses and other submerged-flowering plants. It is relatively rare compared to terrestrial pollination strategies, but represents a well-established adaptation for fertilization in fully aquatic environments.

Evolutionary and ecological significance lies in enabling reproduction in water-dominated habitats, reducing reliance on pollinators, and shaping floral and pollen morphologies to aquatic conditions.