Polygala tenuifoliaPolygala tenuifolia is an herb in the family Polygalaceae which is hardy to USDA Zone 6.PhytochemistryP. tenuifolia contains tenuifolin, senegenin, and polygalacic acid.Medicinal usesYuan zhi is used primarily as an expectorant. It is one of the 50 fundamental herbs used in traditional Chinese medicine, where it is called yuǎn zhì and believed to have neuropsychiatric effects. It has been studied as a potential drug source in depression and Alzheimer's. The quality of the herb varies widely, and as of 2020 there have been no toxicological studies or clinical trials. However, in a March, 2025, meta-analysis of 27 studies with 2,334 samples and 19 natural extract treatments, "he most striking result was that the root extract of Polygala tenuifolia... had the highest ranking for improving overall cognitive function".