Fruits are an adaptation for seed dispersal. The flower and development of a seed in the ovule enclosed in an ovary is only characteristic of angiosperm plants. Still other flowers contain stamens and pistils. After fertilization the entire ovary will enlarge and become the fruit of the plant. Natural pollination may be enhanced by wind, birds, and insects.
Pollen grains have a thick protective wall.
This prevents the dehydration of the pollen grain contents during its transfer from the anther to the stigma. Process of Fertilization and Development in Plants 1. Pollen grain germinates on the stigma and begins to form a pollen tube which extends into the ovule. The pollen tube grows all the way down the style to the ovule of an ovary. The sperm nucleus travels down this tube.