Pollen tube subsequent pollination (transfer of pollen grains to the pistil, the female reproductive organ). Transfer of pollen is usually carried out by wind, water, or animals . The ovaries hold the ovules that produce the female gamete: the egg cell, which waits in place for fertilization. Once a pollen grain settles on a compatible pistil, it may germinate in response to a sugary fluid secreted by the mature stigma. Lipids at the surface of the stigma may also stimulate pollen tube growth for compatible pollen. Plants that are self-sterile often inhibit the pollen grains from their own flowers from growing pollen
Hilum (biology) such a mark, and can be used as a distinguishing characteristic of a seed or spore. Hilum (biology) In botany, a hilum (pronounced ) is a scar or mark left on a seed coat by the former attachment to the ovary wall or to the funiculus (which in turn attaches to the ovary wall). On a bean seed, the hilum is called the "eye". For some species of fungus, the hilum is the microscopic indentation left on a spore when it separates from the sterigma of the basidium. A hilum can also be a nucleus of a starch grain; the