Vernonia is a genus of about 1000 species of forbs and shrubs in the family Asteraceae. Some species are known as ironweed. Some species are edible and of economic value. They are known for having intense purple flowers. The genus is named for the English botanist William Vernon. There are numerous distinct subgenera and subsections in this genus. This has led some botanists to divide this large genus into several distinct genera. For instance, the Flora of North America only recognizes about 20 species in Vernonia sensu stricto, 17 of which are in North America north of Mexico, with the others being found in South America.