Recent molecular investigations of Buddlejaceae s. str. confirmed close phylogenetic relationships among Buddleia, Emorya, Nicodemia, and Gomphostigma and to certain groups within Scrophulariaceae and Lamiales. Buddleia is the largest genus within Buddlejaceae. Although Buddleia has over 90 species distributed in Africa, Asia, and the Americas, only two species have been examined using molecular data. To further test the monophyly of Buddlejaceae 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 Emorya and Gomphostigma, and eight 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 yielded 12 most parsimonious trees (length 419, CI = 0.969) after successive weighting. Our results indicated strong support for: 1) a monophyletic Buddlejaceae s. str. (bootstrap = 100, d = 8) comprising species placed in Buddleia, Emorya, Nicodemia, and Gomphostigma; 2) a paraphyletic Buddleia; 3) exclusion of Nuxia from Buddejaceae; and 4) sister group status for the South African genus Teedia to Buddlejaceae (bootstrap = 100, d = 7). Within Buddleia and segregates, there was strong support for a clade made up of Asiatic species of Buddleia + Nicodemia + Gomphostigma + Emorya. African and most New World species were less resolved but formed a weakly supported clade. Within the trnL-F region, there were higher substitution rates in the IGS region compared to the trnL intron. Comparisons among five ingroup species with sequence data from nrDNA ITS and cpDNA trnL-F indicated that the trnL-F region had higher proportions of informative nucleotide substitutions and informative indels.

Key words: Buddleia, Buddlejaceae, trnL-F