i) Pollination in maize is brought about by the wind and this method is called anemophily. Maize plant has both male and female flowers on each plant. The tassel is the male flower and the ear is the female flower of the plant. Tassel and ear are separated by a distance on an individual plant. ii) Pollination in vallisneria is through water. In vallisneria, the female flowers are submerged in water. They reach the surface of water by the long stalks on reaching maturity. During this period the male flowers are released onto the water surface. The pollens from male flowers come in contact with the female flowers and the pollination is achieved.  iii) Roses are pollinated by insects and this method is called entomophily. The flower is brightly colored and produces nectar. This attracts the insect. When the insect visits the flower pollens stick on its body. When the same insect visits another flower it dusts the pollens on its stigma resulting in pollination.