ABSTRACT
Objective:To find the natural environmental boundary of the origin of the authentic Ligusticum chuanxiong by analyzing the distribution characteristics of soil elements in the traditional geo-authentic area and the southern continuous expanding areas along the same longitude. Method:The contents of 24 elements both in soil and plant L. chuanxiong samples were determined by using X-ray fluorescence spectrometry （XRF） and ICP-MS，etc. Spearman correlation test was used to evaluate the correlations of rhizosphere soil and each portion of L. chuanxiong，to screen out “characteristic elements”. Bray-Curtis similarity indexes based on all elements and "characteristic elements" were used for hierarchical cluster analysis of soil samples, to identify the sample range with similar soil element charateristics to the traditional geo-authentic area of L. chuanxiong. Result:K，Mg，Mn and Rb elements were significantly correlated in rhizosphere soil and plant L. chuanxiong. Geographical differentiation of all elements and four characteristic elements showed that there was a highest similarity between geo-authentic area and its neighbor plots S1-S6 (except plot S4) in soil elements distribution, followed by plots S14-S16. The middle section plots S7-S13 in the expansion areas were quite different from the traditional geo-authentic production areas. Conclusion:The soil element characteristics in the study areas were not completely controlled by geographical distance，but demonstrated the "fault" variation in the areas along longitude. This study provides a theoretical basis for the detrrmination of suitable cultivation area for Ligusticum Chuanxiong, and the natural boundary of its geo-authentic area may be extended an additional 60 km southward along longitude beyond the traditional origin. Additionally， K，Mg，Mn and Rb characteristic elements may be the potential markers to evaluate the suitable soil environment for cultivating L. chuanxiong.