The cashew family, Anacardiaceae, includes about 600 species and has traditionally been subdivided into five tribes (Anacardieae, Dobineae, Rhoeae, Semecarpeae, and Spondiadeae). Results from analysis of sequence data for matK, trnL, and the intergenic spacer between the trnL exon and trnF indicate that this five tribal system is artificial and instead supports two major clades within the family. The larger clade contains members of tribes Rhoeae, Semecarpeae, Dobineae, and Anacardieae while the smaller clade contains tribe Spondiadeae and a few members of tribe Rhoeae. The results, generated from sequence data for these three regions of the chloroplast genome, also support a monophyletic Anacardiaceae, distinct from its sister group, the Gumbo-Limbo family, Burseraceae. The sequence data appear congruent with floral structure characters that distinguish these two families. Within each of the families floral structure is relatively uniform but Anacardiaceae differs from Burseraceae by the number and orientation of the ovules. Conversely, fruit type in Burseraceae is rather invariable while Anacardiaceae has a wide variety of fruit types. There are many unusual fruit characteristics found within the cashew family, such as, the presence of specialized seed germination structures known as opercula and a diversity of evolutionary adaptations for wind dispersal. Preliminary phylogenies generated in this study indicate that opercula have evolved twice and wind dispersed taxa group together in a single clade.

Key words: Anacardiaceae, Burseraceae, matK, trnF, trnL