Immediate precursor to fertilization in .
Pollination is effected by pollen. It involves the attachment of a pollen grain either to the ovule of a gymnosperm or instead to the stigma of a flower. The process then continues with formation of a that transports gamete(s), the nuclei, to the .
In the course of pollination, pollen grains undergo , which results in pollen tube formation. Pollination typically is effected by the or, instead, by various animals .