Fertilization is the process by which fusion of the male and female gametes takes place. Fertilization involves pollen germination, entry of pollen tube into the embryo sac, release of male gametes anti-double fertilization. During pollen germination, the generative nucleus divides to form two male nuclei/gametes which are released into the embryo sac by the rupture of the pollen tube.
One of the gametes passes between the synergids and fuses with the egg cell to form the diploid zygote/oospore and the other fuses with the secondary nucleus to form the trlploldPEN/ primary endosperm nucleus. Since the male gamete participates in two fertilizations it is termed double fertilization and since the formation of the secondary nucleus is already a product of nuclear fusion it represents triple fusion.
