Differentiation of two hemp nettle species (<Emphasis Type="Italic">Galeopsis bifida</Emphasis> Boenn. and <Emphasis Type="Italic">G. tetrahit</Emphasis> L.) inferred from morphological characters and DNA markers

Two species of the genus Galeopsis L., G. tetrahit L. and G. bifida Boenn. (family Lamiaceae), are problematic to distinguish often wrongly recognized, and treated by some taxonomists as a single species. Morphological diagnostical characters of these species are variable and partly overlap. Species independence of G. tetrahit and G. bifida was evaluated and their diagnostic characters verified using ISSR and RAPD markers. A total of 57 ISSR and 28 RAPD fragments were obtained providing distinct subdivision of the accessions examined into two groups. Analysis of molecular data using the neighbor-joining method showed that the accessions studied fell into two clades in the same way as demonstrated by the analysis of 20 morphological characters using single linkage method. These results suggest that G. tetrahit and G. bifida are distinct species. The morphological characters were found to be more variable compared to the molecular markers, although the combined of these characters provided differentiation of the species.