an artifact of some phylogenetic method. The composition of Bignoniaceae has been relatively stable and has not varied at all in the 21st century. In the 20th century, the only issues of circumscription were whether Paulowniaceae and Schlegeliaceae should be merged into Bignoniaceae, or accepted as separate families. The Paulowniaceae consist of one to four genera: Paulownia, Shiuyinghua, Wightia, and Brandisia. Whatever their circumscription, Paulowniaceae are now known to be close to Phrymaceae and Orobanchaceae, rather than to Bignoniaceae. The family Schlegeliaceae has been included in Bignoniaceae, as tribe Schlegelieae, as recently as 1980. It is now accepted as a distinct family, but its relationships with several other families remain unresolved. In molecular phylogenetic analyses, Bignoniaceae has surprisingly weak bootstrap support, given its morphological coherence. The tribe Jacarandeae (Digomphia and Jacaranda) is sister to the rest of the family, which is known as the Core Bignoniaceae. The Core Bignoniaceae is strongly supported in all molecular phylogenetic analyses, but has no known morphological synapomorphy. No subfamilies have been proposed for Bignoniaceae in recent taxonomy, but in 2004, Fischer et al. divided the family into seven tribes: Tourrettieae, Eccremocarpeae, Tecomeae (sensu lato), Bignonieae, Oroxyleae, Crescentieae, and Coleeae. Since that time, Tourrettieae and Eccremocarpeae have been merged under the name Tourrettieae. Tecomeae sensu lato has been shown to be polyphyletic, consisting of the following groups: Astianthus, Jacarandeae, Argylia, Delostoma, Perianthomega, Catalpeae, Tecomeae sensu stricto, and all of Crescentiina except those genera placed in Crescentieae or Coleeae. All of these groups are monophyletic except Crescentiina pro parte. The whole Crescentiina is monophyletic. Crescentiina is one of a type of name with no definite taxonomic rank. Crescentiina is composed of two strongly supported clades, informally named the Tabebuia alliance and the Paleotropical clade. The tribe Crescentieae is embedded in the Tabebuia alliance and might be expanded to include Spirotecoma. Coleeae sensu Fischer et al. (2004) is polyphyletic because of the inclusion of Kigelia, and it is nested within the Paleotropical clade. Perianthomega has been transferred from Tecomeae sensu stricto to Bignonieae, where it is sister to the remainder of the tribe. Thus, Bignoniaceae can be divided into 10 monophyletic groups. Phylogeny The phylogenetic tree shown below is based on the results of four phylogenetic studies. For all clades, posterior probability is at least 0.95 and bootstrap support is at least 70%, except where indicated otherwise. Genera In the last taxonomic revision of Bignoniaceae, 104 genera