What does triple fusion and double fertilisation write the significance of double fertilisation?

Explanation

Triple fusion : One of the two male gametes fuses with the egg cell. This is known as syngamy and the fused product is called an oospore. The other male gamete unites with the Secondary nucleus. This is known as triple fusion (as this involves the fusion of I male nucleus and 2 polar nuclei) and the fused product is called primary endosperm nucleus. (PEN). 
After fertilization the following changes take place.
• Oospore develops into embryo and PEN develops into endosperm
• Ovule develops into seed and integuments of ovule develop into seed coat
• The outer integument of the ovule forms the testa or outer seed coat The inner integument forms the tegmen or inner seed coat. Ovary develops into fruit and ovary wall develops into fruit wall called pericarp.
• Style, Stamiens, calyx and corolla wither of Significance of double fertilization Importance or double fertilization is the production of seeds from ovules and fruits from ovarian Double fertilization signifies the formation of nutritive tissue endosperm in the seed!