Pollination and Fertilization

• When the male and female gametophytes are fully mature, the pollen grains land on the stigma is known as pollination.
• After pollination, the pollens germinate and send the tube called pollen tube through the style and micropyle and finally reach to ovule.
• The tube nucleus soon degenerates and the two gametes (sperms) enter the embryo sac. One sperm fuses with the diploid polar nuclei to form the triploid primary endosperm nucleus.
• Since the fusion involves three haploid nuclei, it is known as triple fusion.
• The second sperm fuses with the egg cell to form a diploid (2n) zygote that forms the embryo.
• Since two male gametes fuse with two different cells, it is called double fertilization.