There are several herbs derived from species of Dioscorea used in Chinese herb formulas, though only two are used with some frequency. By far the most common is Dioscorea opposita (Dioscorea batatas), for which the rhizome (tuber) is used; it is called shanyao (mountain herb). This is in the yam family, and the herb is sometimes simply referred to as "Chinese yam."
Modern pharmacology finds that it has preventive and therapeutic effects on spleen-deficiency, bidirectionally regulates the isolated intestinal movement, helps digestion, promotes cellular and humoral immune responses in mice, lowers blood sugar, inhibits oxidation, and more. In addition, in combination with Licorice Root it can nourish Yin and generate body fluid while combined with Chinese privet it can invigorate the spleen and stop diarrhea.
