Question

Describe fertilization in flowering plants.

Answer 1

The pollen grains which reach sticky stigma, abosrb their secretions, swell up and rupture at one of germ pores. The thin intine emerges out in the form of pollen tube which continues to grow and penetrate deep into the style. The contents of the pollen grains moves into the pollen tube.

The pollen tube enters into the ovule through the micropyle. Inside the embryo sac, the tip of the pollen tube ruptures and 2 male gametes are set free near the egg-apparatus and one of the 2 male gametes fuses with egg nucleus and forms a diploid zygote. This process is called syngamy.

The other male gamete pushes further into embryo sac and fuses with secondary nucleus to form a triploid nucleus called primary endosperm nucleus. This process of fusion is called Triple fusion.

This entire events of fertilization is so called double fertilization.