Fertilization is the union of male and female gametes to form zygote.

Fertilization begins when a pollen grain lands on the stigma of the carpel. Then it bursts open and forms a pollen tube. Pollen tube downwards through the style and finally reaches the ovule in the ovary. The male gamete present in the pollen grain moves through the pollen tube and fertilizes the ovum present in the ovule, i.e., fertilization takes place. The fertilization leads to the formation of zygote which later develops into an embryo. The following picture shows the fertilization in plants: