any of several plants of or developed from the species Dahlia pinnata having tuberous roots and showy rayed variously colored flower heads; native to the mountains of Mexico and Central America and Colombia
source: WordNet 3.0
A genus of plants native to Mexico and Central America, of the order Compositæ; also, any plant or flower of the genus. The numerous varieties of cultivated dahlias bear conspicuous flowers which differ in color.
