Explain the process of fertilisation in plants. tilFIDescribe the mode of fertilization in plants with a diagram.
A.
- Fertilisation is the process of fusion of male and female gametes.
- For the fusion of male and female gametes pollen grains have to reach the surface of the stigma. This is called pollination.
- Pollen grains received by the stigma, germinate and give rise to pollen tubes. Only one pollen tube finally reaches the embryosac.
- This tube will have two male nuclei, which migrate to the tip of the pollen tube at the time of fertilization.
- Usually the pollen tube enters the ovule through micropyle and discharges the two male gametes into its embryosac.
- One male nucleus (gamete) approaches the egg and fuses with it to form a diploid (2n) zygote. This is first fertilisation.
- The 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.
- Thus double fertilisation occurs in embryosac which is unique in flowering plants.