The male parts of a flower are called stamens, which contain anthers that produce pollen grains. The female part is the carpel, which contains the stigma, style, and ovary holding eggs. Pollination is the transfer of pollen grains, either from the same flower (self-pollination) or different flowers (cross-pollination), and can occur through insects, wind or water. After pollen lands on the stigma, a pollen tube grows down through the style into the ovary where fertilization of an egg forms a zygote, completing the sexual reproduction process in flowering plants.