dahlia

Any of the 30 species of tuberous-rooted herbaceous plants that make up the genus Dahlia, in the aster family, native to higher elevations of Mexico and Central America. The leaves of most are segmented and toothed or cut. About six species have been bred for cultivation as ornamental flowers. Wild species have both disk and ray flowers in the flowering heads, but many varieties of ornamentals, such as the common garden dahlia (D. bipinnata), have shortened ray flowers. Dahlia flowers may be white, yellow, red, or purple.

Find more information on dahlia. Upgrade to Britannica Online for more on dahlia.