Dahlia is a genus of bushy, tuberous, perennial plants native to Mexico, Central America, and Colombia. There are at least 36 species of Dahlia. Dahlia hybrids are commonly grown as garden plants. The Aztecs gathered and cultivated the dahlia for food, ceremony, as well as decorative purposes [1], and the long woody stem of one variety was used for small pipes. In 1872 a box of Dahlia roots were sent from Mexico to the Netherlands. Only one plant survived the trip, but produced spectacular red flowers with pointed petals. Nurserymen in Europe bred from this plant, which was named Dahlia juarezii with parents of Dahlias discovered earlier and these are the progenitors of all modern Dahlia hybrids. Ever since, plant breeders have been breeding Dahlias to produce thousands of cultivars, usually chosen for their stunning and brightly coloured flowers. Dahlia plants range in height from as low as 12" (30cm) to as tall as 6-8 feet (180-240cm). The flowers can be as small as 2" (5 cm) in diameter or up to a foot (30 cm) "dinner plate". The great variety results from Dahlias being octoploids (they have eight sets of homologous chromosomes, whereas most plants have only two). Dahlias are used as food plants by the larvae of some Lepidoptera species including Angle Shades, Common Swift, Ghost Moth and Large Yellow Underwing. The dahlia is named after Swedish 18th-century botanist Anders Dahl. In Germany they were known as georgines until recently. They were named by the botanist Carl Ludwig Willdenow after the naturalist Johann Gottlieb Georgi of St. Petersburg, Russia. Bloom forms The American Dahlia Society recognizes 19 distinct bloom forms: * Formal Decorative Judged shows Dahlias are often grown for judged shows. Awards are given for best in class and best in show. Traditionally, dahlias grown for shows have used intensive application of pesticides and inorganic fertilizers. More recently, however, competitive dahlia growers have used organic methods with equally good results.[2] References 1. ^ Harvard Arboretum See also * List of dahlia diseases External links
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