Flowers are the reproductive structures of flowering plants that mediate the union of male sperm and female ovum to produce seeds. They attract pollinators like insects, bats, and birds through traits like scent, color, and nectar guides to facilitate the transfer of pollen between flowers. A flower's form, including the arrangement of stamens and pistils, ensures pollen grains are transferred to the bodies of pollinators. They are made up of four main whorls: sepals, petals, stamens that produce pollen, and a pistil containing ovules.