Photosynthesis of Different Pear (Pyrus L.) Cultivar-rootstock Combinations Advances in studies on chemical constituents in medicinal plants of Pyrus L. and their pharmacological activities Genetic diversty and phylogenetics of pear (Pyrus L.) germplasm resources from Hubei Province revealed by Chloroplast DNA variation Advances in studies on chemical constituents in medicinal plants of Pyrus L. and their pharmacological activities Photosynthesis of Different Pear (Pyrus L.) Cultivar-rootstock Combinations