Explain the process of pollination in Vallisneria .How is it different in water- lily , which is also an aquatic plant ?

Explanation

Hydrophily is of two types, viz., hypo-hydrophily and epihydrophily.
1. Hypohydrophily :
(1) Pollination that takes place with the help of water below the surface of water in hydrophytes bearing submerged female flowers is called hypohydrophily.
(2) Plants showing hypohydrophily produce needle-like pollen grains.
(3) These pollen grains lack exine and possess the same specific gravity as that of water. The refo re they float below the surface of water.
(4) When pollen grains come in contact with stigma, they coil around it and get deposited.
(5) Hypohydrophily is seen in plants like Zostera and Ceratophyllum.
2. Epihydrophily:
(1) Pollination that occurs on the surface of water is called epihydrophily.
(2) Epihydrophily is seen in Vallisneria.
(3) In Vallisneria, male flowers after getting detached from the plant float over the surface of water.
(4) The female flowers in Vallisneria do not detach. They are raised on the long stalks over the surface of water. When pollen grains come in contact with the stigma, pollination is effected.