Define pollination. Explain wind and water pollination with example.

Pollination is the process of transfer of pollen grains from the anther of the stamen to the stigma of the pistil of the flower. It is an important step of sexual reproduction in flowering plants in which gamete transfer takes place. Cross-pollination between different plants occurs with the help of pollinating agents. Wind, water, insects, birds, etc., are act as pollinating agents. Pollination by wind is called anemophily and the flower in which pollination takes place by the wind is called anemophilous flower. Wind-pollinated flowers are small, dull-coloured, odourless and nectar-less. The flowers possess well-exposed stamen or anther and large feathery stigma. These flowers have a single ovule in their ovary. The flowers produce a large number of small pollen grains which are dispersed in air and are non-sticky. These characters help the flower for pollination by wind. Examples: grasses, sedges, oak, etc. Vallisneria is a submerged freshwater aquatic plant. The pollination in Vallisneria occurs through the water. It is known as hydrophily. The pollen grains of this plant have a mucilaginous covering which protects it from wetting.