Dahlia UK deɪliə or US dɑːliə is a genus of bushy, tuberous, herbaceous perennial plants native mainly in Mexico, but also Central America, and Colombia. A member of the Asteraceae (or Compositae), dicotyledonous plants, related species include the sunflower, daisy, chrysanthemum and zinnia. There are 42 species of dahlia, with hybrids commonly grown as garden plants. Flower forms are variable, with one head per stem; these can be as small as 2 in (5.1 cm) diameter or up to 1 ft (30 cm) ("dinner plate").