Male Reproductive Parts

• The male reproductive part in a flower is called the androecium. It consists of a whorl of stamens. Each stamen has a tube-like filament that holds the anther, which holds pollen grains. Each pollen grain has two cells. One cell divides to form the two male gametes, or sperm cells. The sperm cells are haploid, meaning they contain only one set of chromosomes. The other cell forms the pollen tube through which the sperm cells travel to fuse with the ovule during fertilization.
  
  

Female Reproductive Parts

• The female reproductive part is called the gynoecium. It consists of one or more pistils. Each pistil consists of a stigma at the top, an ovary at the base and a style connecting the two. The ovary contains ovules that become seeds after fertilization.
  
  

Ovule

• Each ovule has a megasporocyte or the megaspore mother cell, which divides twice through meiosis to produce four megaspores. Each of these megaspores is haploid. While three of these megaspores degenerate, the one remaining divides through the process of mitosis to form the embryo sac. The embryo sac has eight haploid nuclei contained within seven cells. The central cell has two nuclei. Each of the remaining six cells, including the egg cell, has one haploid nucleus.
  
  

Pollination

• Pollination is the first step in the process of seed formation. Pollination refers to the transfer of pollen grains from the pollen sac of stamens to the stigma of a pistil. Various agents like wind, water and animals such as insects or hummingbirds help in pollination.
  
  

Fertilization

• After pollination has taken place, the pollen grains sitting on the stigma germinate to grow pollen tubes. Pollen tubes carry sperm cells into the ovules. The pollen tube enters the ovule through the micropyle, which is an opening in the outer layer of the ovule. Once inside the ovule, the sperm cells are released. While one sperm fuses with the egg cell to form the diploid zygote, the other sperm cell fuses with the polar cell to form the endosperm. This is the process of double fertilization, which forms seeds from ovules.