Angiosperm Cycle of Reproduction

Angiosperm's reproductive cycle is more complex in comparison to many of the other species of land plants. Angiosperms undergo two main functions: meiosis and fertilization.

The reproductive cycle of the angiosperm begins with the anthers. Anthers contain microsporangiums, or pollen sacs. On the anther, each pollen sacs contains microsporocytes (2n) that would undergo meiosis for division, creating microspores (n). After mitosis it would become a pollen grain (n). The pollen grain contains a generative cell and a tube cell (with a tube nucleus). The generative cell would divide, forming two sperm cells. The tube cell would create the pollen tube. After the pollen grains connect to the stigma, the sperm and the tube nucleus would travel down the pollen tube, this is the process of pollination. After pollination, the sperm cells would eventually be discharged into each ovule. The ovule would already have divided it's megasporocyte in the megasporoangium by the process of meiosis. The product would be four megaspores. Only one would survive to become the female gametophyte that receives the sperm.

Next, there would be double fertilization. One sperm would fertilize the egg, forming a zygote; the other sperm would fertilize the central cell, which would turn into an endosperm (3n) which would act as a food supply. The zygote would then develop into an embryo, which is then packaged along with the endosperm, forming a seed. The seed would eventually germinate and the embryo would develop into a mature sporophyte.

http://www.mun.ca/biology/scarr/139450_Angiospermae.jpg