Abstract: The root tubers of some species of the genus Stephania are known as "Shan-wu-gui" in the indigenous medicine of South and South-western China. In recent years, from these root tubers some useful alkaloids, such as l-tetrahydropalmatine, l-dicentrine cepharanthine, isocorydine, etc., have been isolated for medicinal purposes.The present investigation was undertaken with the aim to find out a method for the determination of the original plants and the drugs of this Chinese folk medicine mentioned above.In the part Of botanical studies of this paper, many specimens bearing the name "Shan-wu-gui", collected primarily from Yunnan and Guangxi, are carefully identified and 17 species of plants, all belonging to the genus Stephania, are recognized, viz. S. kwangsiensis Lo, S. viridiflavens Lo et M. Yang, S. micrantha Lo et M. Yang, S. hainanensis Lo et Y: Tsoong, S. dolichopoda Diels, S. dicentrinifera Lo et M. Yang, S. mashanica Lo et B. N. Chang, S. kuinanensis Lo et M. Yang, S. dielsiana Y. C. Wu, S. succifera Lo et Y. Tsoong, S. yunnanensis Lo, S. longipes Lo, S. brachyandra Diels, S. epigaea Lo, S. cepharantha Hayata, S. sinica Diels, S. excentrtca Lo. An analytical key and a brief critical catalogue of these 17 species are given.The pharmacognostical features of the root tubers of 16 species of these plants are studied in details by thin-layer chromatography of the total alkaloids and the microscopic observations of the powdered drugs. The results (fig. 1 & tab. 1) of thin-layer chromatography demonstrated that these 16 species are different in the composition of the total alkaloids. The powdered drugs, including starch grains, stone cells, and crystals of calcium oxalate, are described with plates of illustrations (tab. 2 & Pl. Ⅰ-Ⅲ).