Theory:

Post fertilization events:
  • After triple fusion, the primary endosperm nucleus develops into an endosperm (the nutritive tissue).
724px-Coconut_layers.svg.png
Endopserm
  • This endosperm serves as nourishment for the developing embryo.
  • After the formation of the endosperm and the zygote, the synergids and antipodal cells degenerate.
  • The ovule develops into the seed.
BeFunky-collage (20).png
Parts of dicot and monocot seeds
  • The integuments of the ovule develop into the seed coat.
  • The ovary develops into the fleshy part known as the fruit.
diagram-41532_1280.png
Structure of fruit and seed
As the seed contains the future plant or embryo, it develops into the seedling under suitable conditions.
 
Germination-en.svg
Seed germination
A video explaining the events of post fertilization
  
Significance of fertilization:
  • The process of fertilization stimulates the ovary to develop into a fruit.
  • Ovules develops into seeds.
  • It also leads to the development of new characters from two different organisms.
Reference:
https://commons.wikimedia.org/wiki/File:Coconut_layers.svg
https://commons.wikimedia.org/wiki/File:Figure_32_02_10.jpg
https://upload.wikimedia.org/wikipedia/commons/2/20/Germination-en.svg
https://commons.wikimedia.org/wiki/File:Dycotyledon_seed_diagram-en.svg