Pollination
As the pollen tube grows, it makes its way from the stigma, down the style and into the ovary. Here the pollen tube reaches the ovule and releases its contents (which include the sperm cells). One sperm makes its way to fertilize the egg cell, producing a diploid (2n) zygote. The second sperm cell fuses with two cell nuclei, producing a triploid (3n) cell.