Euphorbiaceae is one of the most representative families in the caatinga especially on the sand dunes of the middle São Francisco River, in the state of Bahia, Brazil. The survey of Euphorbiaceae species from this formation was based on field work and herbaria collections. The family is represented in the study area by 20 species: Alchornea Swartz (one species); Chamaesyce S.F. Gray (3); Cnidoscolus Pohl (4); Croton L. (4); Dalechampia L. (1); Jatropha L. (3); Manihot Miller (2); Sapium P. Browne (1) and Tragia L. (1). Chamaesyce alsinifolia (Boiss.) Sátiro, C. chamaeclada (Ule) Sátiro, Croton paludosus Mull. Arg., Manihot catingae Ule and M. heptaphylla Ule are endemic to the state of Bahia. Cnidoscolus quercifolius Pohl and C. urnigerus (Pax) Pax are restricted to caatinga regions of Brazil. Identification keys, morphological descriptions, illustrations, notes on geographic distribution, habitat and comments on each species are provided.
Euphorbiaceae; sand dunes; middle São Francisco River; flora
