dahlia

Dahlia
Dahlia x hybrida
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Asterales
Family:	Asteraceae
Subfamily:	Asteroideae
Tribe:	Coreopsideae[1]
Genus:	Dahlia Cav.
Species
30 species, 20,000 cultivars
Synonyms
Georgina Willd.[2]

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, ceremonies, as well as decorative purposes,^[3] and the long woody stem of one variety was used for small pipes.

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 ^[4]. In German the dahlia was known during most of the 19th century as Georgia, being named after the naturalist Johann Gottlieb Georgi of St. Petersburg, Russia.

History

Illustration of a Dahlia

F. Hernández visited Mexico in 1615 and noticed two spectacular varieties of dahlias, which he mentioned in his account of medicinal plants of New Spain, not published until 1651.^[5] The French botanist Nicolas-Joseph Thiéry de Menonville, sent to Mexico to steal the cochineal insect valued for its scarlet dye, noted the strangely beautiful flowers he had seen in his official report, published in 1787.^[6] Seeds sent from the botanical garden of Mexico City^[7] to Madrid flowered for the first time in the botanical garden in October 1789, and were named Dahlia coccinea by Antonio José Cavanilles, the head of the Madrid Botanical Garden, in his Icones plantarum, 1791. A few seeds were secured by Lord Bute and sent to England, where they flowered but were lost.

The introduction of the dahlia to the florists of the Netherlands was effected about the same time, when a box of dahlia roots was sent from Mexico to the Netherlands. Only one plant survived the trip, but produced spectacular red flowers with pointed petals. Nurserymen in Europe crossbred from this plant, which was named Dahlia juarezii, with parents of dahlias discovered earlier and these are the progenitors of all modern dahlia hybrids. The Jardin des plantes in Paris received dahlias in 1802, again from Madrid.^[8] A second species, D. variabilis, was at last successfully grown in 1804 by the gardener at Holland House, Kensington, of Lady Holland, who sent the seeds from Madrid. An early breeder of dahlias was comte Léon-Charles LeLieur de Ville-sur-Arce, intendant of the château de Saint-Cloud, its glasshouses and gardens, who had four varieties to work with,^[9] and by 1806 had produced three double-flowered dahlias.

Since 1813, commercial plant breeders have been breeding dahlias to produce thousands of cultivars, usually chosen for their stunning and brightly coloured waxy flowers. Dahlia was named the national flower of Mexico in 1963.^[10] Dahlia plants range in height from as low as 12 in (30 cm) to as tall as 6–8 ft (1.8–2.4 m). The flowers can be as small as 2 in (5.1 cm) in diameter or up to 1 ft (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).

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.^[11]

Gallery

Dahlia 'Adelaide Fontane'	Dahlia 'Appleblossom'	Dahlia 'Arabian Night'	Dahlia 'Art Deco'
Dahlia 'Asahi Chohji'	Dahlia 'Aspen'	Dahlia 'Akita'	Dahlia 'Aurora's Kiss'
Dahlia 'Heat Seeker'	Dahlia 'Dahlstar Sunset Pink'	Double Dahlia.

Other names

The dahlia is also known as Tenjikubotan (天竺牡丹) in Japanese, which literally means 'Peony of India'. According to the Japanese language of flowers, it means 'good taste'.

See also

• List of dahlia diseases

References

External links

• The United Kingdom National Dahlia Collection
• American Dahlia Society
• North American Dahlia Shows
• 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.

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