We often try to shoe insects away from flowers. We shouldn't do that because insects are essential for the reproduction of flowering plants. How? They help in pollination. We call them pollinating agents. But, what is pollination? Pollination is the transfer of pollen grains from the stamen to the surface of the stigma. How does this transfer take place since plants cannot move? This happens by various means such as wind, water, birds, insects like bees and butterflies, and even mammals like bats. When insects land on a flower to drink nectar, pollen grains stick to their bodies. When they visit other flowers, they carry with them the pollen grains. When pollination occurs within the same flower or the same plant, it is called self-pollination. But, when it occurs between different plants of the same species, it is called cross-pollination. Now, the pollen grain on the stigma absorbs water and begins to swell. It germinates and gives rise to a pollen tube that enters the style. This tube contains the generative cell and the tube nucleus. The generative cell divides to form two sperm cells. The pollen tube elongates to carry the sperm cells to the ovule found inside the ovary. When the pollen tube reaches the ovary, it penetrates the ovule releasing the two sperms. One of the sperm fertilizes the egg to form the zygote. This is fertilization. The other sperm combines with the two polar nuclei to form the endospirm. The zygote grows into an embryo. The endospirm nourishes the growing embryo. Many flowers have an ovary with several ovules. Each ovule requires one pollen tube to be fertilized. Each fertilized ovule becomes a seed and the ovary becomes a fruit.