haploid
microspores -> (mitosis) pollen grain
with 2 sperm + tube cellhaploid
megaspore -> (mitosis) embryo sac
with 8 nuclei.
Pollination occurs when pollen grains
make contact with the stigma (silks)
and develop pollen tubes that grow toward the embryo sac
.
One sperm unites with the oocyte nucleus and the other unites with two endosperm nuclei.
This double fertilization produces a diploid
zygote nucleus and a
triploid
endosperm nucleus.