The polyphenol contents and compositions in desiccated leaves of Myrothamnus flabellifolius plants collected in various locations in Namibia and South Africa were analyzed using UV spectroscopy and high-performance liquid chromatography-mass spectrometry. A study of the genetic relatedness of these populations was also performed by determination of the DNA sequence of the intergenic spacer region between the psbA and the trnH genes in the chloroplast genome. Namibian M. flabellifolius plants contained significantly more polyphenols than South African plants. Namibian plants essentially contained a single polyphenol, 3,4,5-tri-O-galloylquinic acid, whereas South African plants contained a variety of galloylquinic acids including 3,4,5-tri-O-galloylquinic acid together with higher molecular weight galloylquinic acids. Sequence analysis revealed a 1.4% divergence between Namibian and South African plants corresponding to the separation of these populations of approximately 4 x 10(6) years. The significance of the poly-phenol content and composition to the desiccation tolerance of the two populations is discussed.