The term ginseng refers to several species of the genus Panax . For more than 2,000 years, the roots of this slow-growing plant have been valued in Chinese medicine. The two most commonly used species are Asian ginseng ( Panax ginseng C. A. Meyer), which is almost extinct in its natural habitat but is still cultivated, and American ginseng ( P . quinquefolius L.), which is both harvested from the wild and cultivated. Panax ginseng should not be confused with Siberian ginseng ( Eleutherococcus senticosus ). In Russia, Siberian ginseng was promoted as a cheaper alternative to ginseng and was believed to have identical benefits. However, Siberian ginseng does not contain the ginsenosides found in the Panax species, which are believed to be active ingredients and have been studied.