Pollens are released from the male flowers of flowering plants and their size varies from 10-100 microns. They are tiny, granular male reproductive cells found in the flowering plants. Some species are self-pollinating wherein pollination takes place in the same flower. In others, pollen has to be transferred from one plant to another for fertilization to take place. This is known as cross-pollination and one of the medium of transportation of pollens is the wind.