Coreopsideae
Introduction '''Coreopsideae''' is a tribe of flowering plants belonging to the Asteroideae subfamily. It includes widely cultivated genera such as ''Cosmos'' and ''Dahlia''.A similar group has been recognized since 1829, generally as part of the tribe Heliantheae (Cassini, 1819). In the late 20th century, molecular studies caused a slightly redefined version of this group to be recognized as its own tribe, Coreopsideae. The larger version of Heliantheae was split into tribes including Bahieae, Chaenactideae, Coreopsideae, Helenieae and, finally, Heliantheae (''sensu stricto''). Within the tribe, the traditional definition of genera based on flower and fruit characters does not reflect evolutionary relationships as inferred through molecular phylogenetics.The tribe is characterized by shiny green bracts at the base of the flower head in two rows: an inner row of tightly spaced bracts and an outer row of a smaller number pointing downward. It includes five genera that use  carbon fixation: ''Chrysanthellum'', ''Eryngiophyllum'', ''Glossocardia'' (including ''Guerreroia''), ''Isostigma'', and ''Neuractis''. These genera are thought to share a common ancestor and thus a single origin of  carbon fixation.
Genera The 26 Coreopsideae genera recognized by the Global Compositae Database as of April 2022:*''Bidens'' *''Chrysanthellum'' *''Coreopsis'' *''Cosmos'' *''Cyathomone'' *''Dahlia'' *''Dicranocarpus'' *''Diodontium'' *''Ericentrodea'' *''Fitchia'' *''Glossocardia'' *''Goldmanella'' *''Henricksonia'' *''Heterosperma'' *''Hidalgoa'' *''Isostigma'' *''Koehneola'' *''Moonia'' *''Narvalina'' *''Oparanthus'' *''Petrobium'' *''Pinillosia'' *''Selleophytum'' *''Tetraperone'' *''Thelesperma'' *''Trioncinia''
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