Polen, or pollen, is a fine powder produced by flowering plants, including trees, grasses, and weeds. It contains the male gametes of these plants and is essential for reproduction. When pollen is transferred from the male part of a flower to the female part, it can lead to fertilization and the production of seeds. Pollen is also a significant factor in the ecosystem, as it helps in the pollination process, which is often facilitated by bees, butterflies, and other insects. Additionally, pollen can be a common allergen for many people, leading to seasonal allergies known as hay fever.