Phylogenetic relationships within the Gentianales based on ndhF and rbcL sequences, with particular reference to the Loganiaceae

Phylogenetic relationships in the Gentianales with focus on Loganiaceae sen su late are evaluated using parsimony analyses of nucleotide sequence data from the plastid genes rbcL and ndhF. Inter- and intrafamilial relationship s in the Gentianales. which consist of the families Apocynaceae (including Asclepiadaceae), Gelsemiaceae, Gentianaceae, Loganiaceae, and Rubiaceae, ar e studied and receive increased support from the combination of rbcL and nd hF data, which indicate that the Family Rubiaceae forms the sister group to the successively nested Gentianaceae, Apocynaceae, and Loganiaceae, all of which are well supported. The family Gelsemiaceae forms a distinct, suppor ted group sister to Apocynaceae. The Loganiaceae sensu stricto form a stron gly supported group consisting of 13 genera: Antonia, Bonyunia, Gardneria, Geniostoma, Labordia. Logania, Mituasacme, Mirreola, Neuburgia, Norrisia, S pigelia, Strychnos, and Usteria. These genera form two well-supported linea ges. Several members of Loganiaceae sensu Leeuwenberg and Leenhouts, i.e., Androya, Peltanthera, Plocosperma, Polypremum, and Sanango are clearly not members of the Gentianales. The earlier exclusion of Buddlejaceae (includin g Buddleja, Emorya, Gomphostigma, and Nicodemia) as well as the reclassific ation of the genera Nuxia and Retzia to Stilbaceae of the Lamiales are all well supported.