Dahlias are tuberous perennials, and most have simple leaves that are segmented and toothed or cut. The compound flowers may be white, yellow, red, or purple in colour. Wild species of dahlias 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. Dahlias grow well in most garden soils. They begin flowering late in the summer and continue flowering until interrupted by frost in the autumn.
