Pollen grain are produced by the anther in meiosis, most pollen grains contain a single vegetative (non-reproductive cell) and a generative cell. The generative cell contains two nuclei, a generative nucleus and a tube nucleus. The generative nucleus divides to form the male gametes while the tube nucleus forms the pollen tube. The wall of pollen grain has two layers, the inner intine which is made of cellulose and the outer exine, which is a tough layer which prevents dying ...view middle of the document...
g. insects. The ovary of a female plant produces the ovule, in the ovule is the egg cell nucleus which is fertilised by the male nucleus.
Process: Pollination occurs when the pollen grain from a flower of one species lands on the stigma of a flower of the same species, the pollen grain then takes water in and germinates. The tube nucleus then begins to form the pollen tube. Enzymes in the pollen tube digest the way through the style. Within the pollen tube is the nucleus from the pollen grain (generative). The pollen tube enters the embryo sac through the micropyle which is a small whole in the base of the ovule. The generative nucleus enters the ovule and fertilisation then occurs, the haploid generative male nucleus fuses with the haploid female nucleus to give a diploid zygote. The seed and fruit then develop, the zygote becomes an embryo, containing plumule and a radicle. The integuments form the testa or seed coat. The whole ovule forms the seed while the surrounding ovary forms the fruit, with the ovary wall becoming the wall of the fruit.
The seeds are then dispersed, if seeds land in an area where favourable they will germinate.