Explain fertilization in flower

1.	Explain fertilization in flower
Answer» \tFertilisation is the process of fusion of male and female gametes.\tFor the fusion of male and female gametes pollen grains have to reach the surface of the stigma. This is called pollination.\tPollen grains received by the stigma, germinate and give rise to pollen tubes. Only one pollen tube finally reaches the embryosac.\tThis tube will have two male nuclei, which migrate to the tip of the pollen tube at the time of fertilization.\tUsually the pollen tube enters the ovule through micropyle and discharges the two male gametes into its embryosac.\tOne male nucleus (gamete) approaches the egg and fuses with it to form a diploid (2n) zygote. This is first fertilisation.\tThe other male nucleus (gamete) reaches the secondary nucleus (2n) and fuses with it to form endosperm nucleus which will be triploid. This is second fertilization in the embryosac.\tThus double fertilisation occurs in embryosac which is unique in flowering plants.

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