The most comprehensive intergeneric phylogeny of Orchidaceae to date was published two years ago by Cameron et al. This was based on 171 rbcL sequences, and indicated that the family would be best divided into five subfamilies: (Apostasioideae (Cypripedioideae (Vanilloideae (Orchidoideae, Epidendroideae)))). However, bootstrap support for the arrangement of these subclades was poor, and there was little resolution among tribes and subtribes within Epidendroideae, the most diverse group of orchids. More recently, phylogenetic hypotheses for the family have been published or presented using smaller sets of sequences from mitochondrial and nulcear loci. These mostly agree with the rbcL tree, but also suffer from a general lack of resolution and/or internal clade support. To address these issues, two additional plastid loci (atpB and psaB) have been sequenced for the most of the same genera used in the rbcL study. Analysed separately, they differ only slightly from the rbcL tree. In combination, however, the tree is well resolved, and many lineages are supported by the bootstrap. Molecular data sets for Orchidaceae will soon be as numerous as those for other large families, and will allow for a new intrafamilial classification of the family based on well supported phylogenies within the near future.

Key words: atpB, Orchidaceae, psaB, rbcL