Mentha (Nepetoideae, Lamiaceae) is a taxonomically complex genus consisting of 29 species and 11 different hybrids including a number of economically important species among them medical plants used for more than 250 years. Because of its high incidence of polyploidy, diverse morphology, high degree of chromosome number variations and interspecies hybridization, Mentha is considered to be a taxonomical challenge. In this paper, we describe cloning and sequencing of internal transcribed spacers (ITS) 1 and 2 of three mint species: Mentha aquatic L., Mentha longifolia L. (Huds) and Mentha piperita L., collected from natural habitats of Bulgaria. The applicability of ITS1 and ITS2 for molecular fingerprinting and further comparative studies, including the newly obtained ITS1 and ITS2 sequences, was tested in phylogenetic analysis of all eight Mentha species, found in Bulgarian flora.
