Opuntia, Gard. Dict. Abr., ed. 4, 2: 974. 1754 sec. Majure & al. (2012)
- Type: Opuntia vulgaris
- =Nopalea, Cact. Hort. Dyck. (1849): 63-64, 233. 1850 syn. sec. Hunt (2006)
- Type: Nopalea cochenillifera
Opuntia is the second-largest genus of the family Cactaceae. As in all species-rich Cactaceae groups, numerous different generic conceps with a varying number of segregate genera have been suggested for Opuntia. Both, extensive splitting (e.g. Backeberg 1966) or lumping into a broadly defined Opuntia were put forward (Rowley 1958; Benson 1982). The first phylogenetic study by Wallace & Dickie (2002) based on the rpl16 intron found Opuntia in the broad sense to be polyphyletic. For the revised generic classification they presented based on their data, they argued for splitting Opuntia, because otherwise further genera (e.g. Pereskiopsis, Pterocactus) were also nested within Opuntia and merging those would make Opuntia a highly heterogenous assemblage. Therefore Wallace & Dickie suggested reinstating the earlier-proposed Opuntia segregates Austrocylindropuntia, Brasiliopuntia, Consolea, Corynopuntia, Cumulopuntia, Cylindropuntia, Grusonia, Maihueniopsis, Miqueliopuntia, Nopalea, Tephrocactus, and Tunilla. Opuntia s.str. was thus restricted to the taxa with flattened stems and reticulate pollen. This concept was entirely adapted by Hunt (2006), and largely by Nyffeler & Eggli (2010). Griffith & Porter (2009), using data from plastid trnL-F and nuclear ITS, found Opuntia in this restricted sense to additionally include Consolea and Nopalea, the clade including all there genera received 100% support, and both Consolea and Nopalea were also as monophyletic with 100%. The tree resolution, however did not allow an immediate conclusion on the delimitation of these genera. Nopalea used to be separated from Opuntia s.str. because it differs primarily in its hummingbird-syndrome flowers. Nevertheless, it was repeatedly found to be nested in Opuntia (Wallace & Gibson 2002; Griffith & Porter 2009; Bárcenas & al. 2011; Hernández-Hernández & al. 2011; Majure & al. 2012) and is therefore no longer maintained as separate genus. The relationship of Consolea to Opuntia has remained more difficult to resolve, but available data suggest it is not part of Opuntia (see also note under Consolea).