Any of about 300,000 species of flowering plants, the largest and most diverse group within the kingdom Plantae representing approximately 80% of all known green plants now in existence. Angiosperms are vascular seed plants in which the ovule (egg) is fertilized and develops into a seed in an enclosed hollow ovary. The ovary itself is usually enclosed in a flower, that part of the plant that contains the male or female reproductive organs (or both). Fruits derive from maturing floral organs of angiosperm plants, so are characteristic of angiosperms.