Multi-gene analysis provides a well-supported phylogeny of Rosales.

Despite many attempts to resolve evolutionary relationships among the major clades of Rosales, some nodes have been extremely problematic and have remained unresolved. In this study, we use two nuclear and 10 plastid loci to infer phylogenetic relationships among all nine families of Rosales. Rosales were strongly supported as monophyletic; within Rosales all family relationships are well-supported with Rosaceae sister to all other members of the order. Remaining Rosales can be divided into two subclades: (1) Ulmaceae are sister to Cannabaceae plus (Urticaceae+Moraceae); (2) Rhamnaceae are sister to Elaeagnaceae plus (Barbeyaceae+Dirachmaceae). One noteworthy result is that we recover the first strong support for a sister relationship between the enigmatic Dirachmaceae and Barbeyaceae. These two small families have distinct morphologies and potential synapomorphies remain unclear. Future studies should try to identify nonDNA synapomorphies uniting Barbeyaceae with Dirachmaceae.