The largest genera of flowering plants include some 57 groups containing 500 or more described species. Among these, the largest is currently the legume genus Astragalus (milk-vetches), with over 3,000 species. Other familiar large genera include the orchid genus Bulbophyllum, with over 2,000 species, Euphorbia (spurges), with more than 1,800 species, and Carex (sedges), with slightly fewer species than Euphorbia.
The sizes of plant genera vary widely from those containing a single species to genera containing thousands of species, and this disparity became clear early in the history of plant classification. The largest genus in Carl Linnaeus' seminal Species Plantarum was Euphorbia, with 56 species; Linnaeus believed that no genus should contain more than 100 species.
The introduction of infrageneric taxa (such as the subgenus, section and series) in the 19th century, by botanists including Augustin Pyrame de Candolle, allowed the retention of large genera that would otherwise have become unwieldy. E. J. H. Corner believed that studying large genera might enable greater insights into evolutionary biology, and he concentrated his efforts on large tropical genera such as Ficus (figs).