The Bignoniaceae tribe Crescentieae consists of 33 species in three genera. It belongs to a group of Mesoamerican plants putatively adapted for dispersal by the Pleistocene megafauna. Alwyn Gentry hypothesized that the common ancestor of this tribe was similar to the neotropical genus Tabebuia . Previous molecular studies have confirmed this relationship, and have shown that while Bignoniaceae are monophyletic, one tribe, the Tecomeae, is paraphyletic. One of these Tecomeae clades consists of Tabebuia s.l. and the three genera of Crescentieae. This supports a monophyletic Crescentieae but suggests that Tabebuia is paraphyletic unless it is expanded to include Crescentieae. The purpose of this research is to further resolve this relationship. Sequences of the chloroplast genes ndhF, trnL/trnF and the nuclear ribosomal ITS/ETS are being obtained to resolve the relationships within and between Tabebuia and the Crescentieae.

Key words: Bignoniaceae, Crescentieae, phylogeny, Tabebuia