Tongcao, also known as Tongtuomu, Baitongcao, and Datongcao, is mentioned in the "Shennong Bencao Jing". It is the stem pith of Tetrapanax papyriferus (Hook.) K.Koch, a plant of the Araliaceae family. In autumn, the stems of 2-3-year-old Tetrapanax papyriferus are cut down, cut into sections while fresh, and the pith is gently removed using fine wooden roots or round bamboo sticks. The sections are then straightened and dried until completely dry.
【Processing Method】"Xiao Er Wei Sheng Zong Wei Lun Fang": "Slice thinly." "Zheng Zhi Zhun Sheng": "Remove the rough skin and file it finely." Currently, the original medicinal material is taken, impurities are removed, and it is cut into thick slices or sections and dried.
【Appearance of Prepared Slices】Irregular thick slices or cylindrical small sections, white or pale yellow in color, with shallow longitudinal grooves. The cross-section is flat, with a silvery-white luster, and the middle part is hollow or covered with a semi-transparent film. It is light in weight, soft in texture, and slightly elastic. It has no odor and no taste.
【Processing Function】Tongcao has a sweet and mild taste, and a slightly cold nature. It enters the lung and stomach meridians. It has the functions of clearing heat, promoting diuresis, and promoting lactation. It is mostly used for conditions such as red and painful urination due to damp and heat, dysuria with astringency, edema with reduced urine output, and insufficient milk secretion. For example, it is used to treat dysuria with red urine like safflower juice in the Tongcao drink (from "Puji Fang"); it is decocted with Poria cocos peel to treat acute nephritis with ascites (from "Zhejiang Medicinal Plants"). Processing makes the medicinal material clean and facilitates formulation and decoction.
