Generic relationships in Araliaceae: looking into the crystal ball

Abstract

Our understanding of relationships among Apiales and within Araliaceae has progressed considerably in the last decade thanks to numerous molecular phylogenetic studies. It is now clear that traditional infrafamilial systems of classification of Araliaceae fail to reflect evolutionary relationships and that the morphological features on which they were based exhibit high levels of homoplasy. Recent studies have provided a very different picture of relationships in the family, and are rapidly converging on a consensus that allows us to review the status of the 41 genera currently recognised in Araliaceae and to consider alternative circumscriptions for those that are not monophyletic. Twenty-four small and medium-sized genera are unlikely to be modified, whereas five others ( Dendropanax , Oreopanax , Osmoxylon , Pseudopanax and Sinopanax ) may require changes in circumscription. The status of four other small genera is not yet clear, but the two largest genera will require considerable re-alignments: Polyscias (c. 150 spp.), which is paraphyletic with respect to six other genera, and the polyphyletic genus Schefflera (c. 650-900 spp.), which represents five geographically distinct clades. While it is still too early to make formal taxonomic changes to these genera, current evidence suggests that Polyscias sensu lato will likely be realigned into 5–8 geographically coherent genera, while Schefflera sensu lato will be split into 10–16 genera.