Dahlia (UK: /ˈdeɪliə/ DAY-lee-ə, US: /ˈdæljə, ˈdɑːljə, ˈdeɪljə/ DA(H)L-yə, DAYL-yə)[3] is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico and Central America.

Dahlias are members of the Asteraceae (synonym name: Compositae) family of dicotyledonous plants,[4] its relatives include the sunflower, daisy, chrysanthemum, and zinnia.

[5] As members of the family Asteraceae, dahlias have composite flower heads called capitula that are composed of multiple florets arranged in a central disc with surrounding petal-like rays.

Francisco Dominguez, an Hidalgo gentleman who accompanied Hernandez on part of his seven-year study, made a series of drawings to supplement the four volume report.

[11] In 1787, the French botanist Nicolas-Joseph Thiéry de Menonville, sent to Mexico to steal the cochineal insect valued for its scarlet dye, reported the strangely beautiful flowers he had seen growing in a garden in Oaxaca.

[14] In 1824, Lord Holland sent his wife a note containing the following verse:The dahlia you brought to our isle Your praises for ever shall speak; Mid gardens as sweet as your smile,

[20]In 1805, German naturalist Alexander von Humboldt sent more seeds from Mexico to Aiton in England, Thouin in Paris, and Christoph Friedrich Otto, director of the Berlin Botanical Garden.

Willdenow now reclassified the rapidly growing number of species, changing the genus from Dahlia to Georgina; after naturalist Johann Gottlieb Georgi.

D. x pinnata was shown to actually be a variant of D. sorensenii that had acquired hybrid qualities before it was introduced to Europe in the sixteenth century and formally named by Cavanilles.

[33] Sections (including chromosome numbers), with geographical distribution;[34] Only Pseudodendron (D. imperialis) and Dahlia (D. australis, D. coccinea) occur outside Mexico.

Many sources state that the name "Dahlia" was bestowed by the pioneering Swedish botanist and taxonomist Carl Linnaeus to honor his late student, Anders Dahl, author of Observationes Botanicae.

It was probably Abbe Antonio Jose Cavanilles, Director of the Royal Gardens of Madrid, who should be credited with the attempt to scientifically define the genus, since he not only received the first specimens from Mexico in 1789, but named the first three species that flowered from the cuttings.

Dahlia is a genus of the uplands and mountains, being found at elevations between 1,500 and 3,700 m (4,900 and 12,100 ft), in what has been described as a "pine-oak woodland" vegetative zone.

[39] The other main pests likely to be encountered are aphids (usually on young stems and immature flower buds), red spider mite (causing foliage mottling and discolouration, worse in hot and dry conditions) and capsid bugs (resulting in contortion and holes at growing tips).

Dahlias are a source of food for the larvae of some Lepidoptera species including angle shades, common swift, ghost moth and large yellow underwing.

When in active growth, modern dahlia hybrids perform most successfully in well-watered yet free-draining soils, in situations receiving plenty of sunlight.

Taller cultivars usually require some form of staking as they grow, and all garden dahlias need deadheading regularly, once flowering commences.

[42] Horticulturally the garden dahlia is usually treated as the cultigen D. variabilis hort., which while being responsible for thousands of cultivars has an obscure taxonomic status.

[5][23] In 1846 the Caledonia Horticultural Society of Edinburgh offered a prize of 2,000 pounds to the first person succeeding in producing a blue dahlia.

To date, dahlias have only developed five, so the closest that breeders have come to achieving a "blue" specimen are variations of mauve, purples and lilac hues.

These terms were based on shape or colour, and the National Dahlia Society included cactus, pompon, single, show and fancy in its 1904 guide.

[78] In 1805, several new species were reported with red, purple, lilac, and pale yellow coloring, and the first true double flower was produced in Belgium.

One of the more popular concepts of dahlia history, and the basis for many different interpretations and confusion, is that all the original discoveries were single-flowered types, which, through hybridization and selective breeding, produced double forms.

According to Edward Sayers,[84] "it attracted much admiration, and at that time was considered a very elegant flower, it was however soon eclipsed by that splendid scarlet, the Countess of Liverpool".

[85] And even earlier reference can be found in a catalogue from the Linnaean Botanical Garden, New York, 1820, that includes one scarlet, one purple, and two double orange Dahlias for sale.

[86] Sayers stated that "No person has done more for the introduction and advancement of the culture of the Dahlia than George C. Thorburn, of New York, who yearly flowers many thousand plants at his place at Hallet's Cove, near Harlaem.

[citation needed] In 1872 J. T. van der Berg of Utrecht in the Netherlands received a shipment of seeds and plants from a friend in Mexico.

The entire shipment was badly rotted and appeared to be ruined, but van der Berg examined it carefully and found a small piece of root that seemed alive.

In 1874 van der Berg catalogued it for sale, calling it Dahlia juarezii to honor Mexican President Benito Pablo Juarez, who had died the year before, and described it as "...equal to the beautiful color of the red poppy.

[105] The dahlia is considered one of the native ingredients in Oaxacan cuisine; several cultivars are still grown especially for their large, sweet potato-like tubers.