How does pollination occur in angiosperms?

In angiosperms, pollination is the transfer of pollen grains from the anthers to the stigma, which is the receptive surface of the pistil. Because these plants are sedentary, they typically rely on external agents—primarily insects, wind, birds, mammals, and occasionally water—to transport pollen.123

Once pollen lands on a compatible stigma, it germinates and produces a pollen tube that grows down through the style toward the ovule. This process is often regulated by chemical compatibility; if the pollen is from an unrelated species or is genetically incompatible, it may fail to germinate. Many angiosperms also utilize systems of self-incompatibility to prevent self-fertilization and promote genetic diversity.1324

Upon reaching the ovule, the pollen tube releases sperm cells to achieve double fertilization, which initiates the development of the embryo and the endosperm, ultimately transforming the ovule into a seed.13