Dahlia is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico.
Dahlias are members of the Asteraceae family, related to the daisy as well as the sunflower and the chrysanthemum.
There are 42 species and about 20,000 cultivars of dahlia.
This great variety results from dahlias being octoploids — that is, they have eight sets of homologous chromosomes, whereas most plants have only two.
Dahlias have mostly tuberous roots.
The stems are leafy, ranging in height from as low as 30 centimeters (12 inches) to more than 1.8–2.4 meters (6–8 feet).