Phylogenetic Affinities of Datiscaceae Based on an Analysis of Nucleotide Sequences from the Plastid rbcL Gene

Nucleotide sequence data from the large subunit of plastid ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) were used to infer the phylogenetic affinities of Datiscaceae relative to other dicotyledonous angiosperms and to assess whether the family is monophyletic. New rbcL sequence data from members of Datiscaceae and Cucurbitaceae were generated and analyzed with other previously available rbcL sequences. Phylogenetic reconstructions based on parsimony place Datisca closer to representatives of Cucurbitaceae and Begoniaceae than to the other two genera within Datiscaceae. Our results do not support the monophyly of Datiscaceae and suggest that a previous separation of the group at the family level may be warranted. The relationships of the Datiscaceae-Curcurbitaceae-Begoniaceae clade to other groups included in the analysis are unresolved, but analyses with smaller data sets suggest affinities with higher Hamamelidae, among which are several actinorhizal groups. Actinorhizal plants, as a group, may thus be more closely related than has been indicated by recent classification schemes.