Past molecular studies aimed at elucidating tribal relationships in the Asteraceae have revealed a Helenieae-Heliantheae-Eupatorieae (HHE) clade in a somewhat terminal position in subfamily Asteroideae. This interesting result and our interest in elucidating further relationships among these tribes have been the stimulus for the present study. We believed a comprehensive DNA sequencing effort would provide a more robust hypothesis of relationships among the genera of the HHE clade. Sequencing studies have focused on completing data matrices for 26 primers for several genes, introns and spacer regions of the chloroplast genome. The final data matrix contains 16,650 bp for 127 genera of the HHE clade. The regions of the chloroplast genome sampled include the genes matK, ndhF, ndhD, and accD; the introns of rpl16, petB, petD, trnL, and 5’trnK-matK, and the spacers between rpl20-rps12, 23S–16S, accD-rbcL, trnT-trnL, and trnL-trnF. Phylogenetic studies based on this data matrix reveal the polyphyletic composition of tribes Helenieae and Heliantheae as currently circumscribed, with members of tribe Eupatorieae in a highly nested position within a clade with the Peritylinae and Galeana-Villanova clade. Moderate to strong jackknife support has been obtained for most clades in the strict consensus tree.

Key words: Asteraceae, chloroplast DNA, Eupatorieae, Helenieae, Heliantheae, phylogenetics