At the right time, the anther releases pollen grains which are equivalent to animal male sperm. Female parts of a flower are called the pistil , each made up of an ovary with ovules and a stalk-like style with a sticky stigma on top. A flower with both stamens and pistil is called a perfect flower. However, many plants have flowers that are imperfect , that is, only male or only female. Sometimes both types of imperfect flowers occur on the same plant.
Monoecious plants have both male and female flowers on the same plant.
Dioecious plants have only one sex of flower per plant. Both monoecious and dioecious plants generally require cross-pollination. When a pollen grain lands on a receptive stigma, it forms a pollen tube down the style to the ovary. Male genetic material passes down the pollen tube and fertilizes an ovule. Ovules become seeds and the surrounding ovary develops into the fruit. .