Phylogenetic relationships of Theaceae inferred from chloroplast DNA sequence data.

Tribal and generic relationships within Theaceae were investigated using cladistic analyses of chloroplast-encoded rbcL and matK + flanking intergenic spacer region data. Molecular data were employed because recent morphological and anatomical studies of tea (Camellia sinensis) and related plant species provide conflicting support for tribal and generic relationships within the family. Parsimony analyses of separate and combined data consistently identify three strongly supported lineages: Theeae, Stewartieae, and Gordonieae. These data support the broad generic circumscription of Camellia and Stewartia but do not support the recognition of Gordonia sensu lato. Gordonia lasianthus and Gordonia brandegeei are the basal clade in Gordonieae, a position far removed from all other representatives of Gordonia sensu lato (Polyspora and Laplacea) included in this study. This phylogeny most closely mirrors Airy-Shaw's tribe Camellieae [= Theeae] and his two subtribes Stewartiinae and Gordoniinae, first published in 1936. We recognize all three major lineages at the tribal level, although there is weak statistical support for a sister relationship between Gordonieae and Theeae. We also find statistical support for the recognition of the two former subfamilies Theoideae and Ternstroemioideae as two separate families, Theaceae and Ternstroemiaceae.