[Herbological studies on the Chinese crude drug ma-huang--part 2--on the confusion between ma-huang, Ephedrae Herba, and Equisetum plants in Medieval China and Japan].

As we previously reported, ma-huang ([Chinese characters: see text], Ephedrae Herba) has been sometimes used together with mu-zei ([Chinese characters: see text], Equiseti Herba) in medieval China and Japan. We herbologically studied this confusion and found that, in China, the confusion was found in literature in the Song dynasty, and Li Shi-Zhen recorded in Ben-cao-gang-mu that both drugs were morphologically and medicinally the same in the Ming dynasty. Though the main reason why the plant of the genus Equisetum, especially E. ramosissimum Desf., had been substituted for Ephedra plants is thought to be their morphological similarity, the doctors who lived in the area where no Ephedra plants grew might have used Equisetum plants as ma-huang based on Li's description. Owing to this confusion in China, the plants of E. ramosissimum were sometimes imported to Japan as ma-huang, and it caused the tentative use of E. ramosissimum as ma-huang in the middle of the Edo era in Japan.