What is double fertilization in plants?

Double fertilization is a unique process in flowering plants (angiosperms) where two fertilization events take place within the ovule. It involves two male gametes (sperm cells) and two female gametes (an egg cell and a central cell with two polar nuclei). The steps are as follows:

1. One sperm cell fertilizes the egg cell to form a diploid zygote, which will develop into the embryo.
2. The second sperm cell fuses with the two polar nuclei in the central cell to form a triploid cell, which will develop into the endosperm. The endosperm provides nourishment to the developing embryo.

This process ensures that the seed has enough nutrients for embryo development and is a critical aspect of the reproductive cycle in flowering plants.