Dahlia, a genus of plants of the great natural order compositm. According to some authorities three, and according to others only two species are known; the best authorities seem to have generally adopted the latter opinion, recognizing the D. superflua, with its outer involucre reflexed, and the D. frustranea, with its outer involucre spreading, as distinct species; while the D. variabilis is a union of both. The plant is a native of Mexico; and the flowers of all the species and varieties are distinguished by the absence of a pappus, and by a double involucre, the outer being many-leaved and the inner consisting of one leaf divided into eight segments. Alexander von Humboldt is believed to have been the first to introduce the dahlia into Europe, he having in 1790 sent some of the plants to Madrid. The marchioness of Bute carried some thence to England to introduce them there; but these were lost, as well as another importation secured by Lady Holland in 1804. Those introduced into France, however, throve there, and from these roots were finally successfully transplanted to England in 1814. They now became favorite plants in many parts of the continent, and they have been cultivated with great care by gardeners everywhere, on account of the ease with which new and beautiful varieties may be produced.

Almost any wished-for combination has been made to result from careful propagation, and the varieties are now almost numberless. The roots were formerly considered valuable tubers; but their acrid taste rendered them unpalatable, and cattle refused to eat them. They grow in bunches, and are long and spindle-shaped. The stem of the flower springs from the middle of the bunch. The name Dahlia was given in honor of Dr. Dahl, a pupil of Linnaeus; but many botanists of continental Europe call the plant Georgina, in honor of Georgi, professor at St. Petersburg at the close.of the 18th century.

Dahlia.