Pollination

• Pollination is the first step in the double fertilization of flowering plants. Flowers contain both male and female reproductive organs. The male reproductive organs produce pollen. Pollen is produced in pollen sacs in the flower's anthers, which are part of the stamen of a flower. When the pollen is ripe, the anthers burst open and pollen is deposited onto the stamen. The stamen are located the center of a flower, where insects land to partake of nectar. When insects land on the stamen, they transfer the pollen to the female part of the flower, located right next to the stamen, called the pistil. This process of pollen transfer is called pollination.
  
  

Fertilization

• When a grain of pollen lands on the tip, or stigma of a pistil, it sticks to it. Then, it sends a long tube through the mouth of the pistil (the style), which is hollow, to the ovary housed at the bottom. Once the tube has reached the ovary, the pollen grain sends two haploid sperm cells down the tube. One of those sperm cells finds and fertilizes the egg, forming a zygote. The other sperm cell finds and merges with the two nuclei in the center cell of the ovary, forming a triploid cell that will quickly develop into endosperm. These two haploid sperm cells, each going their own way, is why the fertilization of flowering plants is called double fertilization. This process is unique to flowering plants.
  
  

Development

• As the embryo develops, it becomes a seed. The endosperm nurtures the growth of the seed, forming a nutritious layer around the embryo. A hard seed coat forms around the endosperm. Double fertilization also triggers changes in the ovary, which becomes a protective, fleshy cocoon around the seed. This is the fruit of the flowering plant.