Pharmacognostical study of Cynanchum stauntonii and Cynanchum glaucescens, botanical sources of TCM Baiqian / 中草药·英文版

ABSTRACT

Objective: Cynanchum stauntonii and Cynanchum glaucescens are botanical species of Baiqian (Cynanchi Stauntonii Rhizoma et Radix) in Chinese Pharmacopoeia, in which, however, there are no microscopic identification. Therefore, we provided the morphological and microscopic identification of the crude drug for updating Chinese Pharmacopoeia. Methods: Twelve batches of C. stauntonii and three batches of C. glaucescens and their crude drugs were taxonomically, morphologically, and microscopically examined. Results: Taxonomically, C. stauntonii had narrowly lanceolate leaves with acuminate apex and 5mm long petiole; Whereas C. glaucescens was oblong-lanceolate or oblong with rounded or acute apex in leaves, and had very short or no petiole. Morphologically, rhizomes of C. stauntonii and C. glaucescens both had hollow pith, but the hollow pith occupied about a half of the rhizome's diameter in C. stauntonii, whereas only a very small proportion of the overall diameter in C. glaucescens. Moreover, microscopic observation showed the difference in the proportion of xylem and in rhizome transverse-sections of the two species along with the difference in the size of the pith. Finally, laticifers and rhizome epidermal secretory cells were present in the powders of C. stauntonii, but absent from C. glaucescens. Conclusion: Based on observation of morphological and microscopic characteristics, the two species can be distinguished by the size of the pith, proportion of xylem of rhizomes, and crude drug powder characters such as laticifers and secretory cells.