Africa present, America present, NW India present
A genus of c. 44 species, one in Africa, three in the Middle East-NW India, the rest American.
The genus was revised by . It is notoriously difficult to identify material to species. As many species are very often tried in cultivation, the work of Burkart should be used at identification. The key below has been compiled from Verde., Manual New Guin. Legum. (1979) 139 and Burkart (l.c.).