Contributed by Alan S. Weakley and Bruce A. Sorrie
A genus of about 30 species, herbs, of America (once unrelated groups are removed). Recent molecular studies suggest that the relationship between Bidens and Coreopsis (as traditionally circumscribed) is complex, and that changes in taxonomy will be needed to more accurately reflect relationships (Kim et al. 1999; Crawford & Mort 2005). Tadesse & Crawford (2014) have begun this process, removing from Coreopsis some unrelated groups into Electra, Leptosyne, and (perhaps) Heterosperma; two additional clades, traditionally treated in Coreopsis section Pseudoagarista, will likely be removed. It appears likely that the clade consisting of sections Gyrophyllum (C. major, C. delphiniifolia, C. verticillata, and C. tripteris) and Silphidium (C. latifolia) will also be removed.
Ref: Allison & Stevens (2001); Barger et al. (2023); Crawford & Mort (2005); Cronquist (1980); Kim et al. (1999); Schilling, Johnson, & Iacona (2015); Sherff & Alexander (1955); Smith (1976); Sorrie, LeBlond, & Weakley (2013); Strother (2006yy) In Flora of North America Editorial Committee (2006c); Tadesse & Crawford (2014). Show full citations.