Hello dear, 

In plants there is double fertilisation, and in that, one sperm fuses with the egg cell (called syngamy) and the other one fuses with the two central nuclei (triple fusion)  all together known as double fertilization. 

Hence , five nuclei (Two of two male gametes and one egg cell and two plolar nuclei ) are involved in double fertilization..

Hope this helped. 

Good luck!