| Current classifications systems of the genus Ephedra have been based upon a limited number of morphological characters, such as ovulate cone bract, seed number, and habit. Phylogenetic relationships in the genus Ephedra are assessed based on the sequence data from nuclear ITS-1 and from chloroplast rbcL and matK genes. This study indicates that the texture and morphology of ovulate bracts, although widely used for delimiting infrageneric groups, do not reflect the phylogenetic relationships in Ephedra, and that the current classification systems are not natural. Phylogenetic analyses using sequence data from both nuclear and chloroplast genomes suggest an early split between the Old World and the New World species, and the species groupings are largely congruent with their geographic distribution patterns. Contrary to the prevalent assumption that the genus Ephedra is ancient, analysis of rbcL sequence data suggests that the living species are relatively recent, and their diversification might have originated in the Middle Oligocene or the Miocene. |
