The post-fertilization changes that take place in a flower are as follows:

• The formation of zygote which later develops into an embryo and a primary endosperm cell which develops into an endosperm takes place.
• While the sepals, petals and stamens are shed, the pistil remains intact.
• The fertilized ovule develops into seeds.
• The ovary matures into a fruit that later develops a thick protective wall, called the pericarp.
• Seeds after dispersal germinate under favourable conditions which later develop into a new plant.