The flowers appear in the summer and are purple, blue, or white in nature. The plant is cultivated as a garden flower. Several cultivars are available, including the cornflower blue 'Klaus Jelitto', 'Colorwheel', which is white, turning purple over time, and 'Blue Danube', which has a blue flower head with a white center. More unusual cultivars include the pink-flowered 'Rosea' and yellow-flowered 'Mary Gregory'. Like a few other plants (such as some species of Vernonia), it contains vernolic acid, a vegetable oil with commercial applications. The genus is named after Jonathan Stokes (1755–1831), English botanist and physician.