Plant Fertilisation

Pollen grain lands on the stigma and pollen tube grows through the style.
• Haploid generative nucleus divides to form two haploid gametes nuclei that move down the pollen tube.
• Tube grows through embryo sac inside the ovule and the two male gamete nuclei enter the sac.
• One fuses with the egg cell and forms a diploid zygote and the second fuses with two nuclei in the embryo sac, called polar nuclei, to form a triploid cell.
• The diploid zygote divides to form the embryo.
• The triploid cell divides to form the endosperm.