How does the male reproductive cell fertilise the female reproductive

How does the male reproductive cell fertilise the female reproductive cell in flowers of such plants (jpea plants) ?
A. 1) In self pollinated plants anthers are usually present above the stigma.
2) Pollen from the anthers drop on the stigma a process that takes place as the flowers . close for the night and that sometimes occurs before they are completely developed
and ready to open.
3) At the time of pollination slightest movement of the flower’s petals to stimulate the stamen to dislodge its pollen and transfer it to the near by stigma is pea plant.
4) Pollination usually occurs before the flower is fully open.