In the neotropics three major group of Bignoniaceae are represented: Bignonieae, the lianas, Tecomeae, the trees with dehiscent fruits, and Crescentieae, the trees with indehiscent fruits. Previous studies have shown that Bignonieae is monophyletic, and sister to a large group of Tecomeae. One clade within the latter group contains most of the New World Tecomeae and is dominated by Tabebuia, the largest genus of Bignoniaceae. However, this clade also contains Cybistax, Zeyheria, Godmania, Ekmanianthe, and the tribe Crescentieae. Tabebuia as we currently recognize it, is paraphyletic unless these other taxa are included. The purpose of this study is to complete the phylogeny for this clade, and to further explore this unexpected relationship between Tabebuia and the Crescentieae. These two groups are morphologically quite distinct, most notably in their fruit morphology. Tabebuia has fruits that are bilocular and dehiscent, while fruits of Crescentieae vary in their number of locules, but are always indehiscent. Two chloroplast regions are currently being sequenced to achieve this goal: ndhF and trnL-trnF intron and spacer. Current results indicate there are two groups of Tabebuia: one with pink and white flowers, and sclerophyllous leaves, and another with strictly yellow flowers and leaves of a more membranaceous texture. The first group of Tabebuia is very species rich, having radiated throughout the Caribbean, while the second group contains fewer species. However, it is this clade of yellow-flowered Tabebuia that contains tribe Crescentieae. Zeyheria and Godmania are sister taxa, and their position within this group is equivocal. They are sister either to the yellow flowered clade or to this entire group of Tabebuia.

Key words: Bignoniaceae, Crescentieae, ndhF, Tabebuia, trnL-trnF