dahlia

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of several plants of the genus Dahlia native to the mountains of Mexico, Central America, and Colombia, having tuberous roots and showy, rayed, variously colored flower heads.
2. n. The flower head of one of these plants.

Century Dictionary and Cyclopedia

1. n. A genus of plants, natural order Compositæ, of which several species are known, all natives of Mexico and Central America. It is nearly allied to the northern genus Bidens. D. variabilis was introduced into Europe from Mexico early in this century. In its native state the flowers are single, with a yellow disk and dull scarlet rays. Under cultivation there have been developed a multitude of forms, varying in height, in foliage, and especially in the beautiful colors and forms of the flowers. The plant is unable to endure frost, and is perpetuated by its tuberous roots, which are taken up for the winter. Two or three other species are sometimes cultivated.
2. n. [lowercase] A plant of the genus Dahlia.
3. n. [lowercase] In dyeing, a violet coal-tar color consisting of the ethyl and methyl derivatives of rosaniline. It is often called Hofmann's violet, and primula. Its application is limited, as it fades when exposed to light.

Wiktionary

1. n. Any plant of the genus Dahlia, tuberous perennial flowering plants native to Mexico.

GNU Webster's 1913

1. n. (Bot.) 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.

WordNet 3.0

1. n. 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