Step 1: Understanding epihydrophily.
Epihydrophily is a type of pollination that occurs on the surface of water.
Step 2: Example plant.
In Vallisneria, male flowers detach and float on the water surface to reach female flowers.
Step 3: Comparison.
Zostera shows hypohydrophily (pollination under water).
Step 4: Conclusion.
Hence, epihydrophily is observed in Vallisneria.