There are 42 accepted species of flowering plants in the genus Dahlia, according to The Plant List.The Plant List The sectional classification of Dahlia sensu Sørensen (1969)Sørensen, P. D. 1969. Revision of the genus Dahlia (Compositae, Heliantheae-Coreopsidinae). Rhodora 71: 309-365, 367-416. as updated by Saar et al. (2003)Dayle E. Saar, Neil O. Polans and Paul D. Sørensen. A Phylogenetic Analysis of the Genus Dahlia (Asteraceae) Based on Internal and External Transcribed Spacer Regions of Nuclear Ribosomal DNA. Systematic Botany Vol. 28, No. 3 (Jul. - Sep., 2003), pp. 627-639. Stable URL: https://www.jstor.org/stable/25063902 and Hansen (2004)Hansen, H. V. (2004), Simplified keys to four sections with 34 species in the genus Dahlia (Asteraceae-Coreopsideae). Nordic Journal of Botany, 24: 549–553. doi: 10.1111/j.1756-1051.2004.tb01639.x and (2008) is as follows (excluding infraspecific taxa);
Section Pseudodendron Image Scientific name Chromosome Count Distribution D. campanulata 2n = 32 Mexico (Guerrero and Oaxaca) D. excelsa 2n = 32Mexico D. imperialis 2n = 32 Mexico, Belize, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Panama and south into Colombia and Ecuador D. tenuicaulis 2n = 32 Mexico (Oaxaca, Jalisco, Michoacan) Section Entemophyllon Image Scientific name Chromosome Count Distribution D. congestifolia 2n = 34 Mexico (Hidalgo) D. dissecta 2n = 34 Mexico (Tamaulipas) D. foeniculifolia 2n = 34 Mexico (Nuevo León, Tamaulipas) D. linearis 2n = 34 Mexico ( Guanajuato, Querétaro) D. rupicola 2n = 34 Mexico (Durango) D. scapigeroides 2n = 34 Mexico (Guanajuato, Hidalgo, Querétaro) D. sublignosa Dayle E. Saar and Paul D. Sørensen. SIDA, Contributions to Botany Vol. 21, No. 4 (21 December 2005), pp. 2161-2167Elevated from D. dissecta var. sublignosa but still listed as unresolved in The Plant List2n = 34 Mexico (Tamaulipas)
Section Dahlia Subsection Image Scientific name Chromosome Count Distribution Subsection Dahlia D. apiculata 2n = 32 Mexico (Oaxaca, Puebla ) D. atropurpurea 2n = 64 Mexico (Guerrero) D. australis 2n = 32 or 64 Mexico (Chiapas, Oaxaca, Michoacan), Guatemala D. barkeriae 2n = 64 Mexico (Jalisco, Michoacán) D. brevis 2n = 32 D. coccinea 2n = 32 or 64 Mexico D. cordifolia 2n = 32 Mexico (Michoacán) D. cuspidata Mexico (Guerrero ) D. hintonii Mexico (Guerrero ) D. hjertingii Mexico (Hidalgo) D. mollis 2n = 32 Mexico (Hidalgo, Guanajuato, Querétaro) D. moorei Mexico (Hidalgo, Querétaro) D. neglecta Mexico Hidalgo, Guanajuato, Querétaro, Veracruz) D. parvibracteata Mexico ( Jalisco) D. pteropoda 2n = 64 Mexico ( Puebla, Oaxaca) D. purpusii Mexico (Chiapas) D. rudis 2n = 32 Mexico (Distrito Federal, México, Michoacán) D. sherffii 2n = 32 or 64 Mexico (Chihuahua, Durango, Sinaloa, Jalisco) D. scapigera 2n = 32 Mexico (Distrito Federal, Michoacán, Guanajuato, Hidalgo) D. sorensenii 2n = 64 Mexico (Distrito Federal, Michoacán, Hidalgo) D. spectabilis Mexico (San Luis PotosÍ) D. tamaulipana 2n = 32 Mexico (Tamaulipas) D. tenuis 2n = 32 Mexico (Oaxaca) D. tubulata 2n = 32 Mexico (Nuevo León, Tamaulipas, Coahuila) D. wixarika Mexico (Durango, Jalisco)Subsection Merckii D. merckii 2n = 36 Mexico ( Monterrey, Puebla, Nuevo León, Oaxaca)
Section Epiphytum Image Scientific name Chromosome Count Distribution D. macdougallii 2n = 32 Mexico (Oaxaca) Unresolved D. pinnata Type (more properly D. × pinnata)Accepted name in The Plant List, but was not accepted by Saar (2003). Hansen, H. V. and J. P. Hierting. 1996. Observations on chromosome numbers and biosystematics in Dahlia (Asteraceae, Heliantheae) with an account on the identity of D. pinnata, D.rosea and D. coccinea. Nordic Journal of Botany 16: 445-455. Most likely (= D. coccinea × D. sorensenii). D. mixtecana (possibly Section Dahlia or Section Entemophyllon)
See also List of Dahlia cultivars
References