Explain how fertilization takes place after the pollen grains land on the stigma of the receiving flower.

Fertilization: It is the process of fusion of male and female gamete to produce a viable zygote that develops and grows to become a new plant.

Steps of fertilization:

1. Once the pollen lands on the right stigma, the pollen grain absorbs moisture and germinates forming a pollen tube.
2. This pollen tube enters the stigma by crushing the cells and travels through the style and enters the ovule that is in the ovary.
3. The pollen tube carries two male gametes which are formed as a result of division in the generative cell within the pollen.
4. These two male gametes follow the path made by the pollen tube and reach the embryo sac within the ovule.
5. The embryo sac contains an egg in the micropylar end guarded by two synergids.
6. One of the two male gametes fuses with the egg cell and forms the zygote.
7. While the other gamete fuses with the centrally located polar nuclei forming the primary endosperm nucleus.