Surface pollination

Surface pollination is more frequent, and appears to be a transitional phase between wind pollination and true hydrophily. In these the pollen floats on the surface and reaches the stigmas of the female flowers as in Hydrilla, Callitriche, Ruppia, Zostera, Elodea. In Vallisneria the male flowers become detached and float on the surface of the water; the anthers are thus brought in contact with the stigmas of the female flowers. Surface hydrophily has been observed in several species of Potamogeton as well as some marine species.