Double Fertilization Double fertilization is complex mechanism of fertilization in flowering plants or angiosperms. Double
fertilization is joining of a female gametophyte with two male gametes. One sperm nucleus fertilizes the egg
cell and the other sperm combines with the two polar nuclei of the megagametophyte. The haploid sperm
and haploid egg combine to form a diploid zygote. The other sperm nucleus fuse with the other two haploid
polar nuclei of the megagametophyte to form a triploid nucleus, this develops into a endosperm and is called
the primary endosperm nucleus. This entire phenomenon of fertilization that involves the fusion of the egg
and one male gamete and the fusion of the other male gamete with the secondary or the polar nuclei is called
double fertilization.
