The dahlia was named in honor of Swedish botanist Andreas Dahl, a student of Linnaeus. They are native to Mexico and Central America. Published reports claim the Aztecs used dahlias to treat urinary difficulties. The first dahlias cultivated outside their native environment were grown in Madrid, Spain, in the late 1700s. Dahlias are members of the Compositae family and are related to daisies. Dahlias are seasonal, which means they will not be available online when out of season.