What is SYNGAMY , DOUBLE FERTILIZATION and TRIPLE FUSION?

The process of double fertilisation occurs in angiosperms.

Here, one of the 2 male gametes fuses with the egg nucleus and forms a diploid zygote (in a process called syngamy). The other male gamete pushes further into the embryo sac and fuses with the secondary nucleus and gives rise to a triploid nucleus called the primary endosperm nucleus (in a process called triple fusion)

This entire phenomenon of fertilisation involving the fusion of one male gamete with the egg, together with the union of the second male gamete with the secondary nucleus or the polar nuclei is called as double fertilisation.

Syngamy can be defined as the process of fusion of egg nucleus with male gamete to form a diploid zygote.

Triple fusion can be defined as the fusion involving two polar nuclei and a sperm nucleus that occurs in double fertilization in a seed plant, giving rise to a triploid nucleus called the primary endosperm nucleus, which later develops into the endosperm.