Abstract:The original plant of Shangzhou Zhiqiao,the best among thespecies of Zhiqiao,is confirmed as Citrusaurantium rather than Poncirus trtjofia in this paper based on the description and drawings of Zhiqiao inIBencao Gang-muby l.i Shizhen in the 1 6th century ,samples from Shangzhou (Shanxi Provincel, and the cold-warm periixl of his-torical climate in the local area,which is believed to be related to the distribution of C. aurantium, in Shangzhou. How-ever,P.trijofia has often been confused with C.auruntium by some herhalists.