Polygala (Yuan Zhi) root comes from *Polygala tenuifolia* or *Polygala senega*. People take it for calmness and memory. Traditional preparations include dried root decoctions, powdered extracts, and liquid tinctures. Typical daily doses are 3 to 9 grams of raw root or 0.3 to 0.9 grams of extract.
High or prolonged doses may harm the liver. Animal studies report neurotoxicity. Do not take Polygala during pregnancy. It can increase drowsiness when taken with central nervous system depressants such as sedatives or alcohol.