Authentication of Bistortae Rhizoma and its three adulterants based on their macroscopic morphology and microscopic characteristics

Bistortae Rhizoma (Quanshen), a dried rhizome of Polygonum bistorta L., is edited in Chinese Pharmacopiea as only one of species of Polygonum. There are many adulterants were used as Quanshen such as "Eryeliao," "Taipingyangliao" and "Daogenliao" because of its remarkable functions. Previous researches had shown that there were not significant differences among them. Therefore, it is necessary to conduct a comprehensive authentication of these herbs samples. Analyses of the microscopic features of the powders and transverse sections of herbs are the most significant measures of accreditation of the quality of traditional Chinese medicine. In this study, microscopic observation of powders of the herbs and cross-sectional tissues were performed by using common light microscopy, polarized light microscopy and combining PCA analysis to identify Quanshen and three adulterants. We found that calcium oxalate clusters can be a good microscopic marker index to distinguish Quabshen and Eryeliao. In addition, Quanshen and the other two can be further distinguished by the characteristics of cork layer cells and vascular bundles on transverse section of the rhizome. Our results showed that the approach, microscopic features and digital characterization, is efficient, convenient, and reliable.