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 th e phylogenetic affinities of Datiscaceae relative to other dicotyledon ous 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 monophyl y of Datiscaceae and suggest that a previous separation of the group a t the family level may be warranted. The relationships of the Datiscac eae-Curcurbitaceae-Begoniaceae clade to other groups included in the a nalysis are unresolved, but analyses with smaller data sets suggest af finities with higher Hamamelidae, among which are several actinorhizal groups. Actinorhizal plants, as a group, may thus be more closely rel ated than has been indicated by recent classification schemes.