Double fertilization:
1. In flowering plant germinated pollen grain forms pollen tube.
2. The end of the pollen tube ruptures and two male garnets are released in the Embryosac.
3. Out of two male garnets one male garnet fuses with female garnet which is called fertilization.
4. Another male garnet fuses with the secondary nucleus and forms endosperm.
5. So in flowering plant fertilization occures twice hence it is called double fertilization.
Uses of Endosperm:
1. Cotyledons develops by utilizing endosperm.
2. The Cotyledons utilizes the stored food in the endosperm.
3. Some of the plants utilizes the endosperm completely and changes in to seed.
4. Because of the stored food the size of the cotyledons increases.