Define triple-fusion. What product is formed from this fusion? What is the ultimate fate of this fusion product?

Explanation

Triple fusion. In the embryo sac both the male gametes are released. One of these nucle fuses with the egg nucleus resulting in the formation of diploid zygote. The process is called syngamy or true or generative fertilisation.
The other male gamete fuses with two polar nuclei (secondary nucleus) and results in the formation of a triploid Primary Endosperm Nucleus (PEN). Since, the process involves fusion o three haploid nuclei (two polar nuclei and one male gamete), it is known as Triple fusion or vegeative fertilisation
The fusion product is Primary Endosperm Cell (PEC) having triploid endosperm nucleus, The PEN divides and ultimately forms multicellular triploid nutritive trissue called as endosperm.