[Species and medical history of "Xishuang" medicinal materials]

"Xishuang" is a special phenomenon that chemical composition of medicinal materials crystallize on the surface exposed to air for a long time. We summarized Herbal textual research of "Xishuang" phenomenon of six herbs, such as Schisandrae Chinensis Fructus, Moutan Cortex, Atractylodis Rhizoma, Magnoliae Officinalis Cortex, dried persimmon frost and watermelon frost. From historical perspective, cream of Schisandrae Chinensis Fructus was firstly discovered in Lei Gong's Moxibustion Theory. Thereafter, dried persimmon frost was found in Song Dynasty, which was named "white persimmon" in Ben Cao Tu Jing and had become an independent medicine in Compendium of Materia Medica. Then, watermelon frost was found in Yang Yi Da Quan of the Qing Dynasty, and Moutan Cortex's "sand star" was recorded in Zeng Ding Wei Yao Tiao Bian of the Republic of China. After that, "Xishuang" phenomenon of Atractylodis Rhizomaand Magnoliae Officinalis Cortex were reported in 1950s and 1960s in succession. The pattern of "Xishuang" is divided into different type, natural "Xishuang" includes Schisandrae Chinensis Fructus, Moutan Cortex, Atractylodis Rhizoma and Magnoliae Officinalis Cortex, artificial "Xishuang" includes watermelon frost, and dried persimmon frost formed crystals by using artificial intervention. The above 6 kinds of herbs have different crystal structure and chemical composition. Therefore, according to traditional identification experience, "Xishuang" phenomenon is related to varieties and quality of medicinal herbs. These research provide herbalism basis for the modern study of "Xishuang" medicinal materials.