How do pollen grains on a stigma cause the fertilization of egg cells?
Flower Anatomy The sticky female part in the center of the flower is called the stigma. A long tube called the style connects the stigma to the ovary, which contains a number of ovules, each of which contains one egg cell. The ovule is surrounded by a protective layer of tissue called the integument. The male part of the flower, which produces pollen grains, is called the anther or stamen. A mature pollen grain contains two cells: a tube cell, which develops into the pollen tube, and a generative cell, which develops into sperm. The pollen grain consists of a tough spore wall on the outside, the tube cell contained within the spore wall, and the generative cell inside the tube cell. Pollination Pollen grains can be transported from one flower to another by animals such as bees, or carried by wind currents. Flowering plants can also self-fertilize, when pollen is transferred from the anther to the stigma within a single flower. Germination When a pollen grain lands on a stigma, it stick
