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 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 cells and germs cells. The tube cells grow into a pollen tube, with 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 stigma, receptacle ovary, and style. Its tube cell sticks to the receptive stigma and starts to develop into a pollen tube. The male germs cell release two sperm cells that travel to reach the flower's ovum. While the male grows the female cell in the ovule develops. One of the sperm cells fuses the egg, while the other forms an endosperm tissue, which serves to nourish the growing zygote or seeds. After fertilization occurs, the ovary wall becomes a fruit.