Jatropha (Euphorbiaceae) is a large and morphologically diverse genus in subfamily Crotonoideae, tribe Jatropheae, and is considered to be the most primitive member of the family. It has an interesting, disjunct, geographical distribution: species are native to seasonally dry, tropical regions with about two-thirds of the species in the Americas, most of the remainder in tropical Africa, and a few in Arabia and India. The genus is so diverse in vegetative and floral morphology that it has been subject to radically different classifications by past as well as modern taxonomists.
In Flora Neotropica, Volume 110: Jatropha (Euphorbiaceae), which includes only the neotropical taxa (United States to Argentina and the West Indies), the two sub-genera have been retained as previously recognized. Subgenus Jatropha includes four sections and seven subsections. Subgenus Curcas is strictly Mesoamerican, with all but two species occurring in Mexico. Of notable interest is the newly erected subsection Fremontioides of section Platyphyllae, which shares some characteristics with subgenus Jatropha and others with subgenus Curcas.
The taxonomic history with the addition of some new information is presented as well as a discussion of lectotypification of the genus. Results of previously published studies of morphological, anatomical, phenetic, and phylogenetic analyses as well as some recent work are used as the bases of classifications.