The flowering plants (angiosperms), also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by characteristics including flowers, endosperm within the seeds, and the production of fruits that contain seeds. Etymologically, angiosperm means a plant that produces seeds within an enclosure, in other words, a fruiting plant.

The ancestors of flowering plants diverged from gymnosperms around 245-202 million years ago, and the first flowering plants known to exist are from 160 million years ago. They diversified enormously during the early Cretaceous Period and became widespread around 120 million years ago, but replaced conifers as the dominant trees only around 60-100 million years ago.

The great angiosperm radiation, when a great diversity of angiosperms first appeared in the fossil record, occurred in the mid-Cretaceous (approximately 100 million years ago). By the late Cretaceous, angiosperms appear to have dominated environments formerly occupied by ferns and cycadophytes, but large canopy-forming trees replaced conifers as the dominant trees only close to the end of the Cretaceous 66 million years ago or even later, at the beginning of the Tertiary. The radiation of herbaceous angiosperms occurred much later. Many fossil plants recognizable as belonging to modern families (including beech, oak, maple, and magnolia) had already appeared by the late Cretaceous.

It is generally assumed that the function of flowers was to involve mobile animals in their reproduction processes. That is, pollen can be scattered even if the flower is not brightly coloured or oddly shaped in a way that attracts animals. By expending the energy required to create such traits, angiosperms could then enlist the aid of animals and, thus, reproduce more efficiently.

Animals are also thought to have been involved in the distribution of seeds. Fruit, which is formed by the enlargement of flower parts, is frequently a seed-dispersal tool that attracts animals to eat or otherwise disturb it, incidentally scattering the seeds it contains. Although many such mutualistic relationships remain too fragile to survive competition and to spread widely, flowering proved to be an unusually effective means of reproduction and spreading to become the dominant form of land plant life.

Flower evolution continues to the present day. Modern flowers have been so profoundly influenced by humans that some of them cannot be pollinated in nature. Many modern domesticated flower species were formerly simple weeds, which sprouted only when the ground was disturbed. Some of them tended to grow with human crops, perhaps already having symbiotic companion plant relationships with them, and the prettiest did not get plucked because of their beauty, developing a dependence upon and special adaptation to human affection.