Three of those break down, and the other one divides several times to produce 8 nuclei. In the microsporangium, the microsporocytes divide meiotically to produce microspores. When a pollen grain lands on the stigma, a pollen tube develops which grows downward until it reaches the ovary. One sperm fuses with the egg and the other fuses with the two polar nuclei of the female gametophyte. The ovary wall eventually becomes the fruit, and the ovules become mature seeds.
Fruits can play an important role in dispersal.
Flowering There is generally some transition from vegetative growth to flowering. If a vegetative meristem becomes an inflorescence meristem, either modified structures such as bracts or flowers can be produced. Plants respond to a critical day length. Short-day plants flower when the day is shorter than a critical maximum. Long-day plants flower when the day is longer than a critical minimum.