Fertilization in flowering plants involves the fusion of the male and female gametes. Pollinators, such as butterflies, bees and birds, pollinate the ovum or egg and transfer the male gametes to a flower’s female reproductive organs. Pollination occurs between two flowers of the same or different plants or within one flower only.
The male component of fertilization in flowering plants is pollen. It consists of two or three gametophytes containing the tube cell and germ cell. The tube cell grows into a pollen tube, while the germ cell divides through mitosis. Pollination brings the male pollen into the female stigma of a flower with the help of pollinators. Large flowers mostly attract insect pollinators, while smaller flowers use the wind to pollinate. The pollen is then transferred into the pistil or gynoecium, which contains the stigma, receptacle, ovary and style. Its tube cell sticks to the receptive stigma and starts to develop into a pollen tube. The male germ cell releases two sperm cells that travel to reach the flower’s ovum. While the male cell grows, the female cell in the ovule develops. One of the sperm cells fuses with the egg, while the other forms an endosperm tissue, which serves to nourish the growing zygote or seed. After fertilization occurs, the ovary wall becomes a fruit.