Saposhnikoviae radix (SR) is described in the Japanese Pharmacopoeia as a crude drug derived from the root of Saposhnikovia divaricata Schischkin (Umbelliferae). According to Flora of China, the root of Peucedanum ledebourielloides K. F. Fu is used as a regional substitute for SR. Therefore, we surveyed the botanical origin of the drug used in China, especially Shaanxi and the surrounding regions, through nucleotide sequence analysis of the internal transcribed spacer region of rDNA. As a result, several samples from Shaanxi (..) and Shanxi (..) provinces were identified as Peucedanum ledebourielloides. To prevent this substitute from being distributed as genuine SR, we developed a thin- layer chromatography analysis condition to enable a specific compound of this species to be easily detected. The specific compound was identified as xanthalin, based on 1D- and 2D- NMR and high- resolution mass spectrometry data. The established TLC conditions were as followsextraction solvent, n- hexane; applied volume, 5 mu L; chromatographic support, silica gel; developing solvent, n- hexane: ethyl acetate: acetic acid (20: 10: 1); developing length, 7 cm; detection, UV (365 nm); Rf value, 0.4 (blue fluorescence; xanthalin).