Phylogenetic relationships between some members of the subfamily Lamioideae (family Labiatae) inferred from nucleotide sequences of the rbcL gene

Total DNA was extracted from 25 species (8 general of the subfamily Lamioideae sensu Erdtman (family Labiatae). Using rbcl-specific primers, the rbcL gene was amplified by polymerase chain reaction (PCR) and 1420 bp were sequenced directly, or after cloning. RbcL sequences were evaluated with character-state (maximum parsimony; PAUP) and distance methods (neighbour-joining; MEGA). In agreement with classical systematics all taxa studied cluster outside the Nepetoideae. The following clades are apparent: I - Westringia/Prostanthera, II - Ajuga/Teucrium and III - Scutellaria, Stachys, Lamium and Marrubium. Lamium album, L. amplexicaule and L. garganicum appear as a sister clade to Marrubium. Both share a common ancestor with a second Lamium clade (including L. purpureum, L. maculatum and L. galeobdolon). The phylogenetic relationships are discussed with regard to the systematic classification of the subfamilies Lamioideae and Nepetoideae (sensu Erdtman).