Editing Dahlia (section)

== Taxonomy==

=== Taxonomic history ===

==== Early history ====
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Spaniards reported finding the plants growing in Mexico in 1525, but the earliest known description is by [[Francisco Hernández de Toledo|Francisco Hernández]], physician to [[Philip II of Spain|Philip II]], who was ordered to visit Mexico in 1570 to study the "natural products of that country". They were used as a source of food by the indigenous peoples, who both gathered wild specimens and cultivated crops.<ref name=":0">[http://arnoldia.arboretum.harvard.edu/pdf/articles/1705.pdf Harvard Arboretum]</ref><ref name="autogenerated2002">Katz, Solomon H.; Weaver, William Woys Weaver, Encyclopedia of Food and Culture, The Gale Group, New York, 2002.</ref> The indigenous peoples variously identified the plants as "Chichipatl" ([[Toltecs]]) and "Acocotle" or "Cocoxochitl" ([[Aztecs]]). From Hernandez's perception of [[Nahuatl]] to [[Spanish language|Spanish]] (through various other translations) the word is "water cane", "water pipe", "water pipe flower", "hollow stem flower", or "cane flower", all referring to the hollow plant stems.<ref>Safford, W.E., "Notes on Dahlias", Journal of the Washington Academy of Sciences, 1919.</ref>

Hernandez described two varieties of dahlias (the pinwheel-like ''[[Dahlia pinnata]]'' and the huge ''Dahlia imperialis'') as well as other medicinal plants of New Spain. 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. Three of his drawings showed plants with flowers: two resembled the modern bedding dahlia, and one resembled the species ''[[Dahlia merckii]]''; all displayed a high degree of doubleness.<ref>Hernandez, Francisco, Nova Plantarum Animalum et Mineralium Historia. Pg. 31-32,372. 1651.</ref> In 1578, a manuscript titled ''Nova Plantarum, Animalium et Mineralium Mexicanorum Historia'', was sent back to the [[Escorial]] in Madrid.<ref>Hernández, ''Rerum medicarum Novae Hispaniae thesaurus'' (Rome, 1651); details of the introduction of the dahlia to European gardens are taken from {{Harvtxt|Harshberger|1897}}</ref> It was translated into Latin by Francisco Ximenes in 1615. In 1640, Francisco Cesi, President of the ''Academia dei Lincei'' of Rome, bought the Ximenes translation and, after annotating it, published it in 1649–1651 as two volumes, ''Rerum Medicarum Novae Hispaniae Thesaurus Seu Nova Plantarium, Animalium et Mineralium Mexicanorum Historia''. The original manuscripts were destroyed in a fire in the mid-1600s.<ref>{{cite journal | last1 = Baltet | first1 = Charles | year = 1906 | title = Comment le Dahlia est arrive du Mexique en Europe | journal = Revue Horticole | volume = 78 | pages = 209–212 }}</ref>

====European introduction====
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 | caption1 = ''Dahlia coccinea'', parent of European "single" dahlias (i.e., displaying a single row of ligulate florets)

 | image2 = Dahlia sambucifolia 1805.png
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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.<ref>Menonville, ''Traité de la culture du nopal et de l'education de la cochenille dans les colonies françaises de l'Amérique'' 1787.</ref> In 1789, [[Vicente Cervantes]], director of the Botanical Garden at Mexico City, sent "plant parts" to Abbe [[Antonio José Cavanilles]], director of the [[Real Jardín Botánico de Madrid|Royal Gardens of Madrid]].<ref>From the director, Sr. Vicentes Cervantes, according to Augustin Legrand and Pierre-Denis Pépin, ''Manuel du cultivateur de dahlias'', "Introduction en Europe", Paris, 1848, p. 10.</ref> Cavanilles flowered one plant that same year, then the second one a year later. In 1791 he called the new growths "Dahlia" for [[Anders Dahl]].<ref name=Cavanilles/> The first plant was called ''Dahlia pinnata'' after its [[pinnate]] foliage; the second, ''Dahlia rosea'' for its rose-purple color. In 1796, from the parts sent by Cervantes, Cavanilles flowered a third plant, which he named ''[[Dahlia coccinea]]'' for its scarlet color.

In 1798, Cavanilles sent ''D.&nbsp;pinnata'' seeds to [[Parma]], Italy. That year, the Marchioness of Bute, wife of [[John Stuart, 1st Marquess of Bute|the Earl of Bute]], the English Ambassador to Spain, obtained a few seeds from Cavanilles and sent them to [[Kew Gardens]], where they flowered but were lost after two to three years.<ref name="autogenerated5">Dean, Richard, The dahlia: its history and cultivation, Macmillan, 1897, p.5.</ref>

[[File:Holland House in 1907 by J. Benjamin Stone - Dahlia Garden.jpg|thumb|right|The Dahlia Garden at Holland House in 1907]]
In the following years Madrid sent seeds to Berlin and Dresden in Germany, and to Turin and Thiene in Italy. In 1802, Cavanilles sent tubers of "these three" (''D.&nbsp;pinnata, D.&nbsp;rosea, D.&nbsp;coccinea'') to Swiss botanist [[Augustin Pyramus de Candolle]] at University of Montpelier in France, [[Andre Thouin]] at the [[Jardin des Plantes]] in Paris and Scottish botanist [[William Aiton]] at Kew Gardens.{{sfn|Weland|2015|loc=p.&nbsp;8}} That same year, John Fraser, English nurseryman and later botanical collector to the Czar of Russia, brought ''[[D. coccinea|D.&nbsp;coccinea]]'' seeds from Paris to the [[Chelsea Physic Garden|Apothecaries Gardens]] in England, where they flowered in his greenhouse a year later, providing ''Botanical Magazine'' with an illustration.
In 1804, a new species, ''Dahlia sambucifolia'', was successfully grown at [[Holland House, London|Holland House]], Kensington. Whilst in Madrid in 1804, [[Elizabeth Fox, Baroness Holland|Lady Holland]] was given either dahlia seeds or tubers by Cavanilles.<ref>{{cite book|last=Forbes|first=James|author2=John Russell Bedford|title=Hortus woburnensis|publisher=J. Ridgway|year=1833|page=[https://archive.org/details/hortuswoburnens00forbgoog/page/n282 246]|url=https://archive.org/details/hortuswoburnens00forbgoog}}</ref> She sent them back to England, to Lord Holland's librarian at Holland House, who successfully raised the plants<ref>{{cite book|last=Hogg|first=Robert|author-link=Robert Hogg (biologist)|title=The Dahlia; Its History and Cultivation|publisher=Groombidge and Sons|year=1853|page=[https://archive.org/details/dahliaitshistor00hogggoog/page/n34 5]|url=https://archive.org/details/dahliaitshistor00hogggoog}}</ref><ref>{{cite journal|journal=Transactions of the Horticultural Society of London|date=1808-04-05|volume=1|page=93|location=London|publisher=W. Bulmer & Co.|title=Observations on the different Species of Dahlia, and the best Method of Cultivating them in Britain.|last=Salisbury|first=R. A.}}</ref> and produced two double flowers a year later.{{sfn|Weland|2015|loc=p.&nbsp;2}} The plants raised in 1804 did not survive; new stock was brought from France in 1815.<ref name="autogenerated5"/> In 1824, Lord Holland sent his wife a note containing the following verse:<blockquote>The dahlia you brought to our isle<br />
Your praises for ever shall speak;<br />
Mid gardens as sweet as your smile,<br />
And in colour as bright as your cheek.<ref>{{cite book|last=Ward|first=Bobby J.|title=A Contemplation Upon Flowers|publisher=Timber Press|year=1999|page=119|url=https://books.google.com/books?id=n3MgSchHBjYC|isbn=978-0-88192-469-5}}
</ref></blockquote>

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]]. More significantly, he sent seeds to botanist [[Carl Ludwig Willdenow]] in Germany. Willdenow now reclassified the rapidly growing number of species, changing the genus from ''Dahlia'' to ''Georgina''; after naturalist [[Johann Gottlieb Georgi]]. He combined the Cavanilles species ''D.&nbsp;pinnata'' and ''D.&nbsp;rosea'' under the name of ''Georgina variabilis''; ''D.&nbsp;coccinea'' was still held to be a separate species, which he renamed ''Georgina coccinea''.

===Classification===
[[File:Close up of a Dahlia x cultorum Thorsrud & Reisaeter.jpg|thumb|Close up of a Dahlia x cultorum Thorsrud & Reisaeter in [[Piracicaba]], Brazil]]
Since 1789 when Cavanilles first flowered the dahlia in Europe, there has been an ongoing effort by many growers, botanists and taxonomists, to determine the development of the dahlia to modern times. At least 85 species have been reported: approximately 25 of these were first reported from the wild; the remainder appeared in gardens in Europe. They were considered [[hybrid (biology)|hybrid]]s, the results of crossing between previously reported species, or developed from the seeds sent by Humboldt from Mexico in 1805, or perhaps from some other undocumented seeds that had found their way to Europe. Several of these were soon discovered to be identical with earlier reported species, but the greatest number are new varieties. [[Morphological variation]] is highly pronounced in the dahlia. [[William John Cooper Lawrence]], who hybridized hundreds of families of dahlias in the 1920s, stated: "I have not yet seen any two plants in the families I have raised which were not to be distinguished one from the other.<ref>Lawrence, W.J.C. "The Genetics and Cytologogy of Dahlia variabilis", ''Journal of Genetics'', July 24, 1931, p. 257.</ref> Constant reclassification of the 85 reported species has resulted in a considerably smaller number of distinct species, as there is a great deal of disagreement today between systematists over classification.{{sfn|Weland|2015|loc=p.&nbsp;13}}

In 1829, all species growing in Europe were reclassified under an all-encompassing name of ''D.&nbsp;variabilis, Desf.'', though this is not an accepted name.{{sfn|Bates|2015|loc=[http://www.dahliaworld.co.uk/dahlia.htm Dahlia types and international classification of dahlias]}} Through the interspecies cross of the Humboldt seeds and the Cavanilles species, 22 new species were reported by that year, all of which had been classified in different ways by several different taxonomists, creating considerable confusion as to which species was which. As of now Dahlias are classified into 15 different species by botanist [[Liberty Hyde Bailey]].<ref>{{Cite web |title=Stanford Dahlia Project Dahlia Hybridization History |url=https://web.stanford.edu/group/dahlia_genetics/dahlia_history.htm |access-date=2023-12-12 |website=web.stanford.edu}}</ref>

In 1830 William Smith suggested that all dahlia species could be divided into two groups for color, red-tinged and purple-tinged. In investigating this idea Lawrence determined that with the exception of ''D.&nbsp;variabilis'', all dahlia species may be assigned to one of two groups for flower-colour: Group I (ivory-magenta) or Group II (yellow-orange-scarlet).{{citation needed|date=September 2020}}

=== Modern classification ===
The genus ''Dahlia'' is situated in the [[Asteroideae]] [[subfamily]] of the [[Asteraceae]], in the [[Coreopsideae]] [[Tribe (biology)|tribe]]. Within that tribe it is the second largest genus, after ''Coreopsis'',<ref name=Saar/> and appears as a well defined [[clade]] within the Coreopsideae.<ref>{{citation | title = Phylogeny of Coreopsideae (Asteraceae) using ITS sequences suggests lability in reproductive characters | author = Rebecca T. Kimballa, Daniel J. Crawford | journal = Molecular Phylogenetics and Evolution | volume = 33 | year = 2004 | pages = 127–139 | doi = 10.1016/j.ympev.2004.04.022 | pmid = 15324843 | issue = 1 | bibcode = 2004MolPE..33..127K }}</ref>

=== Subdivision ===

====Infrageneric subdivision ====
{{See also|List of Dahlia species}}
Sherff (1955), in the first modern taxonomy described three sections for the 18 species he recognised, ''Pseudodendron'', ''Epiphytum'' and ''Dahlia''.<ref>Sherff, E. E. 1955. Dahlia. Compositae-Heliantheae-Coreopsidinae. [[North American Flora]]. Part 2:45–59. [[New York Botanical Garden]]</ref> By 1969 Sørensen recognised 29 species and four sections by splitting off ''Entemophyllon'' from section ''Dahlia''.<ref name=Sorensen69>{{cite journal | last1 = Sørensen | first1 = P. D. | year = 1969 | title = Revision of the genus Dahlia (Compositae, Heliantheae-Coreopsidinae) | url = https://archive.org/stream/mobot31753003413934/mobot31753003413934_djvu.txt | journal = Rhodora | volume = 71 | issue = 309–365| pages = 367–416 }}</ref> By contrast Giannasi (1975) using a [[phytochemical]] analysis based on [[flavonoids]], reduced the genus to just two sections, ''Entemophyllon'' and ''Dahlia'', the latter having three subsections, ''Pseudodendron'', ''Dahlia'', and ''Merckii''.<ref>David E Giannasi. The flavonoid systematics of the genus Dahlia (comstoopidpositae). ''Memoirs of the New York Botanical Garden'', 26,2. New York Botanical Garden, 1975.</ref> Sørensen then issued a further revision in 1980, incorporating subsection ''Merckii'' in his original section ''Dahlia''.<ref>{{cite journal | last1 = Sørensen | first1 = P. D. | year = 1980 | title = New taxa in the genus Dahlia (Asteraceae, Heliantheae-Coreopsidinae) | url = https://archive.org/stream/mobot31753003488282/mobot31753003488282_djvu.txt | journal = Rhodora | volume = 82 | pages = 353–360 }}</ref>
When he described two new species in the 1980s (''[[Dahlia tubulata]]'' and ''[[Dahlia congestifolia|D.&nbsp;congestifolia]]''), he placed them within his existing sections.<ref>{{cite journal | last1 = Sørensen | first1 = P. D. | year = 1987 | title = Dahlia congestifolia, Section Entemophyllon (Asteraceae: Heliantheae, Coreopsidinae), new from Hidalgo, Mexico | journal = Rhodora | volume = 89 | pages = 197–203 }}</ref> A further species, ''[[Dahlia sorensenii]]'' was added by Hansen and Hjerting in (1996).<ref>{{cite journal | last1 = Hansen | first1 = H. V. | last2 = Hierting | first2 = J. P. | year = 1996 | title = Observations on chromosome numbers and biosystematics in Dahlia (Asteraceae, Heliantheae) with an account on the identity of D. pinnata, D. rosea and D. coccinea | journal = Nordic Journal of Botany | volume = 16 | issue = 4| pages = 445–455 | doi=10.1111/j.1756-1051.1996.tb00256.x}}</ref> 
At the same time they demonstrated that ''[[Dahlia pinnata]]'' should more properly be designated ''D.&nbsp;x pinnata''. ''D.&nbsp;x pinnata'' was shown to actually be a variant of ''D.&nbsp;sorensenii'' that had acquired hybrid qualities before it was introduced to Europe in the sixteenth century and formally named by Cavanilles.<ref name=Cavanilles>{{cite book |last= Cavanilles |first= A. J. |author-link= |year= 1791 |title= Icones et Descriptiones Plantarum |url= https://www.loc.gov/resource/gdcwdl.wdl_15013_001/?sp=138&st=image&r=0.084,0.648,1.24,0.607,0 |location= Madrid, Spain |volume= 1 |page=57 |via= [[Library of Congress]]}}</ref> The original wild ''D.&nbsp;pinnata'' is presumed extinct. Further species continue to be described, Saar (2003) describing 35 species.<ref name=Saar/> However separation of the sections on morphological, cytologal and biocemical criteria has not been entirely satisfactory.<ref name=Saar/>

To date these sectional divisions have not been fully supported [[phylogenetically]],<ref name="Kamenetsky">{{cite book |url=https://books.google.com/books?id=5B-ucdbgA3wC |title=Ornamental Geophytes: From Basic Science to Sustainable Production |publisher=CRC Press |year=2012 |isbn=978-1-4398-4924-8 |editor-last1=Kamenetsky |editor-first1=Rina |location=Boca Raton, Florida, USA |editor-last2=Okubo |editor-first2=Hiroshi}}</ref> which demonstrate only section ''Entemophyllon'' as a distinct sectional [[clade]]. The other major grouping is the core ''Dahlia'' clade (CDC), which includes most of the section ''Dahlia''. The remainder of the species occupy what has been described as the variable root clade (VRC) which includes the small section ''Pseudodendron'' but also the monotypic section ''Epiphytum'' and a number of species from within section ''Dahlia''. Outside of these three clades lie ''D.&nbsp;tubulata'' and ''D.&nbsp;merckii'' as a [[polytomy]].<ref name=Saar/>

Horticulturally the sections retain some usage, section ''Pseudodendron'' being referred to as 'Tree Dahlias', ''Epiphytum'' as the 'Vine Dahlia'. The remaining two herbaceous sections being distinguished by their [[pinnules]], opposing (''Dahlia'') or alternating (''Entemophyllon'').<ref>[http://www.dahlia-nds.co.uk/about_dahlias/Specie_Dahlia.htm National Dahlia Society: Dahlia species]</ref>

===== Sections =====
Sections (including [[chromosome numbers]]), with geographical distribution;<ref>{{cite journal | last1 = Hansen | first1 = H. V. | year = 2004 | title = Simplified keys to four sections with 34 species in the genus Dahlia (Asteraceae-Coreopsideae) | journal = Nordic Journal of Botany | volume = 24 | issue = 5| pages = 549–553 | doi = 10.1111/j.1756-1051.2004.tb01639.x }}</ref>
* ''Epiphytum'' Sherff (2n = 32)
**10 m tall climber with aerial roots 5&nbsp;cm thick and up to more than 20 m long; pinnules opposite
** 1 species, ''D.&nbsp;macdougallii'' Sherff 
** Mexico: Oaxaca
* ''Entemophyllon'' P. D. Sorensen (2n = 34)
** 6 species
** Mexico: Hidalgo, Nuevo León, Tamaulipas, Querétaro, Durango, San Luis Potosí 
* ''Pseudodendron'' P. D. Sorensen (2n = 32)
** 3 species + ''D.&nbsp;excelsa'' of uncertain identity
** Mexico: Chiapas, Guerrero, Jalisco, Michoacan, Oaxaca, and Costa Rica, El Salvador, Guatemala & Colombia
*  ''Dahlia'' (2n = 32, 36 or 64)
** 24 species
** Mexico: Distrito Federal, Guerrero, Hidalgo, Morelos, Nuevo León, Puebla, San Luis Potosí, Tamaulipas, Veracruz, Oaxaca, Puebla, Chiapas, México, Huehuetenango, Chihuahua, Durango, Michoacan & Guatemala

Only ''Pseudodendron'' (''[[Dahlia imperialis|D.&nbsp;imperialis]]'') and ''Dahlia'' (''D.&nbsp;australis'', ''D.&nbsp;coccinea'') occur outside Mexico.

=====Species=====
{{main|List of Dahlia species}}
There are currently 42 accepted species in the genus ''Dahlia''<ref>{{cite web |title=Dahlia |url=http://www.theplantlist.org/1.1/browse/A/Compositae/Dahlia/ |website=The Plant List |archive-url=https://web.archive.org/web/20190413220709/http://www.theplantlist.org/1.1/browse/A/Compositae/Dahlia/ |archive-date=13 April 2019}}</ref> but new species continue to be described.<ref name=Kamenetsky/>

===Etymology===
The naming of the plant itself has long been a subject of some confusion. 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''. However, Linnaeus died in 1778, more than eleven years before the plant was introduced into Europe in 1789, so while it is generally agreed that the plant was named in 1791 in honor of Dahl, who had died two years before,<ref>Stafleu, F. A.; Cowan, R.S., Taxonomic literature, vol. 1: A–G, Utrecht, 1976.</ref> Linnaeus could not have been the one who did so. 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.{{sfn|Weland|2015|loc=p.&nbsp;2}}

Regardless of who bestowed it, the name was not so easily established. In 1805, German botanist [[Carl Ludwig Willdenow]], asserting that the genus ''Dahlia'' Thunb. (published a year after Cavanilles's genus and now considered a synonym of ''[[Trichocladus]]'') was more widely accepted, changed the plants' genus from ''Dahlia'' to ''Georgina'' (after the [[Germany|German]]-born naturalist [[Johann Gottlieb Georgi]], a professor at the Imperial Academy of Sciences of [[St. Petersburg]], [[Russia]]).<ref>Willdenow. Species Plantarum. Ed. 4. vol. 3. pt. 3. pp. 2124-2125. 1800.[https://www.biodiversitylibrary.org/item/14564#page/650/mode/1up]</ref> He also reclassified and renamed the first three species grown, and identified, by Cavanilles. It was not until 1810, in a published article, that he officially adopted the Cavanilles's original designation of ''Dahlia''.<ref>Willdenow von, The Dahlia, Enumeratio Plantarum. Hor. Reg. Bot. Berolinensis, 899, 1809.</ref> However, the name ''Georgina'' still persisted in Germany for the next few decades. In Russian, it is still named Georgina ({{langx|ru|георгинa}}).