Recent molecular investigations of Buddlejaceae s. str. have confirmed close phylogenetic relationships among Buddleia, Emorya, Gomphostigma, and Nicodemia, and to certain groups within the Scrophulariaceae and Lamiales. With over 90 species distributed in Africa, Asia, and the Americas, Buddleia is the largest genus within this smaller and monophyletic Buddlejaceae s.str., yet only two species have been examined using molecular data. To further test the monophyly of the Buddlejaceae s. str. and to elucidate phylogenetic relationships among species of Buddleia and segregate genera, we examined nucleotide variation from the trnL-F region of the plastid genome among 23 species of Buddleia, two species of Nicodemia, one species each from Chilianthus, Emorya, and Gomphostigma, and 10 outgroup taxa. From an aligned length of 1029 bp, exclusion of gaps resulted in 778 sites and 79 informative characters. Seven indels were identified as parsimony informative, when treated as binary characters. Maximum parsimony analyses of the combined data matrix yielded 12 most parsimonious trees (length 419) after successive weighting. Our results indicated: 1) strong support (bootstrap = 100, d = 8) for a monophyletic Buddlejaceae s. str. comprising Buddleia, Chilianthus, Emorya, Gomphostigma, and Nicodemia, 2) exclusion of Nuxia from Buddejaceae, and 3) strong support (bootstrap = 100, d = 7) for the South African genera Teedia and Oftia as sister to Buddlejaceae. Within Buddleia and segregates, there was strong support for a clade made up of Asiatic species of Buddleia + Nicodemia + Gomphostigma + Emorya. The African and New World taxa were less resolved and more poorly supported. Within the trnL-F region, there were higher substitution rates in the IGS region than the trnL intron. Among five ingroup species with ITS sequences, the plastid trnL-F region had higher proportions of informative nucleotide substitutions and informative indels.

Key words: Buddleia, Buddlejaceae, trnL-F