dahlia

dahlia [for Anders Dahl, 1751-89, Swedish botanist and pupil of Linnaeus], any plant of the genus Dahlia of the family Asteraceae (aster family), tuberous-rooted perennials native to Mexico and Guatemala and widely cultivated in gardens. Most of the several thousand horticultural varieties have been developed from the single species (D. pinnata) of garden dahlia introduced into cultivation in England c.1800, but other species and hybrids, e.g., the cactus dahlia (D. juarezii) are also grown. Dahlias are stout and rather woody plants, some species reaching the stature of small trees, with late-blooming flowers in a wide range of colors and sizes. The tubers of the garden dahlia were one source of fructose, used by diabetics. Dahlias are classified in the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae.

Dahlia is a genus of bushy, tuberous, perennial plants native to Mexico, Central America, and Colombia. There 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 , 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.

Cultivar

Dahlia Dahlstar Sunset Pink is a miniature Dahlia cultivar with pink flowers that shade to yellow in the centre. Height and spread are 15 cm.

Bloom forms

The American Dahlia Society recognizes 19 distinct bloom forms:

• Formal Decorative
• Informal Decorative
• Straight Cactus
• Semi Cactus
• Incurved Cactus
• Laciniated
• Ball
• Mini Ball
• Pom
• Waterlilly
• Stellar
• Novelty Fully Double
• Novelty Open Center
• Anenome
• Single
• Collerette
• Orchid
• Mignon Single

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.

Gallery

References

See also

• List of dahlia diseases

External links

• The United Kingdom National Dahlia Collection
• American Dahlia Society
• The National Dahlia Society of New Zealand
• Dahlia Flower Care
• Info about care for dahlias
• Dahlia rosea at pfaf
• Dahlia pinnata at pfaf
• Gallery of Dahlia Images
• Dahlia species
• The medicinal and nutritional properties of Dahlia spp.