Pollen grains are tiny, powdery structures produced by the male reproductive organs of flowering plants, known as anthers. They contain the male gametes necessary for fertilization. Each grain is typically made up of a tough outer layer called the exine, which protects the genetic material inside. When pollen grains are transferred to the female reproductive parts of a flower, called the stigma, they can fertilize the ovules, leading to the formation of seeds. Pollen is also a crucial part of the ecosystem, as it is a primary food source for many bees and other pollinators.