Mains Miller belongs to sub-family Maloidae of Rosaceae family in plant taxonomy. There were thirty to thirty-five recognized species of the genus in the world, which distributed mainly in Asia, Europe and North America from subtropical to tropical mountainous areas in the world. Among them twenty to twenty-three, at least, were found in China. If the eight new species published in recent years were accounted, there are thirty-one Mains species in China. About the exact number of the species in g...