The blueberry tribe is a large and morphologically diverse group that is widespread in the temperate and tropical zones of most continents. It is morphologically distinct from remaining members of Ericaceae s.l. in its possession of an inferior ovary. Among the approximately 40 genera described within Vaccinieae, Vaccinium is the largest and most widespread, occurring in both the Old and New World temperate and tropical latitudes. In the Neotropics 3035 genera are recognized compared to only four or five recognized genera in the Old World tropics. This study sampled 93 species of Vaccinieae, representing 30 genera, and 17 sections (of the approximately 33 currently recognized) of Vaccinium. For each species, sequence data from the chloroplast matK gene and the nrITS were obtained. Each data set was analyzed separately and then as a combined matrix. Strict consensus trees generated from the individual data analyses did not indicate any strongly supported conflicting relationships. In the strict consensus of the combined analysis seven clades (most weakly supported) form a polytomy at the base of the tree. However, several well supported (bootstrap) clades (provisionally named for discussion purposes only) were found. These include: an Andean clade composed of representatives of 19 of the 23 Neotropical genera sampled (excluding Vaccinium), a Meso-American/Caribbean clade, a Malesian clade including the Old World taxa Paphia and Dimorphanthera, an Agapetes clade comprised of some Asian Vaccinium and Agapetes, and a Bracteata-Oarianthe clade (Vaccinium spp.). These results indicate that Vaccinium is not monophyletic and suggest that Vaccinium represents a grade group out of which several tropical groups have evolved. This study also indicates that several other genera currently recognized in Vaccinieae are likely not monophyletic. These include the Old World genera Dimorphanthera, Paphia, and Agapetes, and the Neotropical genera Diogenesia, Orthaea, Thibaudia, Sphyrospermum, and Disterigma.

Key words: Ericaceae, molecular systematics, tropical blueberries, Vaccineae, Vaccinium