After pollination, the pollen grains have to find a way of getting from the stigma to the ovary where it would be more useful.
This brings about what we will term as fertilisation. By definition, this is simply the process by which the male gametes and the female gametes join to form a diploid cell , the zygote.
So how does the pollen get to the ovary?
Each ovule consist of a large oval shaped cell called embryo sac. The mature embryo sac contains a number of nuclei including the female nucleus or ova.
A tip of the pollen tube is attracted towards the micropyle and passes through it to enter the embryo sac the tip of the pollen tube then bursts and the vegetative nucleus disintergrates.
One of the two male nuclei fuses with one female nucleus to form the diploid zygote.After fertilization it undergoes cell division to form the embryo. Later it divides mitotically and differentiates into the radicle, plumule and cotyledons of the seed.
The other fuses with both polar nuclei to form a triploid nucleus.This is known as the primary .endosperm nucleus. Later this triploid nucleus divides mitotically into a mass of nuclei which become separated from one another by thin cell walls. This becomes a semi-solid food storage tissue called the endosperm which surrounds the developing embryo and provides it with nourishment.
The ovule forms the seeds and the ovary the fruit.
Generally fertilization is the fusion of the female and male gametes to form a zygote.
Fertilisation , is essentially the crucial mode of reproduction in those organisms that undergo sexual reproduction. For plants, as we know already, the male gametes are the pollen grains and the female gametes are the ovules. These must join inorder to reproduce.
Double fertilization, that is , as exhibited above, where two male gametes fuse with female cells is unique to flowering plants.
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