Flower
A flower is the reproductive structure of a flowering plant, bearing organs that produce gametes and enable fertilization and seed formation.
Sepal: A usually green, leaflike floral part that encloses and protects a developing flower bud. Sepals form the outermost floral whorl and shield the flower before it opens.
Pollination: The transfer of pollen from an anther to a receptive stigma or, in some plants, directly to an ovule. Pollination places pollen where it can participate in the flower's reproductive process.
Floral symmetry: The pattern by which a flower can be divided into similar halves, commonly radial or bilateral. Symmetry influences which pollinators can approach and handle a flower.
Angiosperm: A flowering plant whose seeds develop enclosed within an ovary that usually matures into fruit. Flowers are the defining reproductive structures of angiosperms.
Gymnosperm: A seed plant whose ovules are not enclosed in an ovary when pollinated. Gymnosperms reproduce without the enclosed ovary characteristic of flowering plants.
Petal: A floral part, often colorful or scented, that can attract pollinators or protect reproductive organs. Petals surround the reproductive organs and often help attract animal pollinators.
Pollen tube: A tubular extension of a pollen grain that grows toward an ovule and carries sperm cells. After pollen germinates on a compatible stigma, its tube delivers sperm to an ovule.
Pollination syndrome: A set of floral traits associated with pollination by a particular group of animals or by wind or water. Color, scent, shape, and nectar can indicate how a flower is adapted for pollen transfer.
Angiosperm phylogeny: The evolutionary relationships among flowering plant lineages, inferred from morphological and molecular evidence. Phylogenies provide the framework for reconstructing how floral forms diversified.
Complete flower: A flower possessing sepals, petals, stamens, and carpels. It is one floral form, distinguished by having all four commonly recognized organ types.