Explain post-fertilization events. Describe the steps of post-fertilization.

(N/A) Post-fertilization events in flowering plants include all the processes that occur after the fusion of gametes (syngamy) to form a zygote. These events are essential for the development of the seed and the fruit.
$1$. Endosperm Development: The primary endosperm nucleus $(PEN)$ undergoes successive nuclear divisions to give rise to free nuclei (free-nuclear endosperm). Later,cell wall formation occurs,making it cellular. It provides nutrition to the developing embryo.
$2$. Embryo Development: The zygote undergoes mitotic divisions to form a proembryo,which then develops into globular,heart-shaped,and finally a mature embryo with a radicle and plumule.
$3$. Seed Formation: The ovule matures into a seed. The integuments of the ovule harden to form the seed coat (testa and tegmen).
$4$. Fruit Formation: The ovary develops into a fruit,and the ovary wall transforms into the pericarp. The floral parts like sepals and petals often wither and fall off.