Taxonomic study on endemic plant Rosa baiyushanensis Q.L.Wang in Liaoning, China

Rosa baiyushanensis Q. L. Wang is an endemic, second-class protected plant in Liaoning Province, China, found only in the Lushun area of Dalian. It was first described by Qingli Wang in 1984 based on three herbarium specimens collected in Baiyu Mountain in Lushun, Dalian, Liaoning Province. During our field work, however, we found no species corresponding to the holotype specimen in Baiyu Mountain, which is likely due to human disturbance and habitat destruction. In the Lushun range, not far from Baiyu Mountain, the species was found in Guojiagou, Duizhuanggou, and other areas. In addition, Rosa canina L., a species native to Europe, was found near Rosa baiyushanensis. Considering that the above places have experienced considerable human disturbance and were occupied by Russia in the 20th century, we conclude that both species are exotic plants. Through field observation, reference to flora, and comparison of external morphology of type specimens of Rosa baiyushanensis and Rosa rubiginosa L., we determine that the former is not essentially different from the latter. Therefore, Rosa baiyushanensis is reduced to synonymy of Rosa rubiginosa L. Furthermore, it is suggested that Rosa baiyushanensis should be removed from the protected list. In Flora of China, Rosa baiyushanensis (Rosa rubiginosa L.) is placed in Section Cinnamomeae, but it belongs in Section Caninae according to Rehder's Classification of Roses. In Flora Reipublicae Popularis Sinicae, Rosa baiyushanensis and Rosa canina L. are not included and the discovery of these two species fills a gap in the distribution of Section Caninae in China.