Angiosperms is the technical name for flowering, sexually reproducing plants. Strictly, angiosperms are the plants that develop their seeds from ovules within a closed cavity, the ovary. They have gradually expanded in diversity since the Cretaceous: in doing so, they have replaced the gymnosperms (conifers and ferns) as the dominant terrestrial plants.
It has been suggested that the coevolution between angiosperms and insects who disperse their seeds may have been important in the radiation of flowering plants. This is shown in the illustration opposite of a bee collecting pollen from a flower.