The microsporangia in the male strobile rupture at the right period of the year releasing thousands of pollen grains. Since their pollen grains are “winged” they can be transported by the wind over distances. When the pollen grains fall into the female strobiles they pass the micropyle and enter the pollen chamber. This process is called pollination.
Within the pollen chamber the generative cell nucleus divides forming two gametic nuclei and the tube cell elongates forming the pollen tube. The pollen tube penetrates the female gametophyte and the gametic nuclei (also known as sperm nuclei) pass through the tube; one of them unites with an oosphere (the female gamete) and forms the zygote (2n). Generally fecundation occurs one year after pollination and during this time interval the maturation of the male and of the female gametes takes place.
The fecundation in these plants is independent from water. The gametophytes however are entirely dependent on the sporophyte (the adult plant) for nutrition and hydration.
