Stephania tetrandra is a herbaceous perennial vine of the Menispermaceae family. It grows from a short, woody caudex, climbing to a height of around four meters. The leaves are arranged spirally on the stem, and are peltate, i.e. with the leaf petiole attached near the centre of the leaf. Its root is used medicinally. Stephania alkaloids have curare-like action, and can selectively inhibit T-cell-dependent immune reactions. The root contains many isoquinoline alkaloids: tetradrine (0.6-0.9%), fangchinoline (0.5%), cyclanoline (0.1%) and dimethyltetrandrine iodide (muscle relaxant). The root also contains flavanoids. The main active alkaloids are: tetrandrine (12 to 23 grams/kg) and fangchinoline (0.3–3 mg/kg). Also present are: dimethyltetradine iodide, cyclanoline, menisine, menisidine, oxofangchirine, stephenanthrine, stepholidine and bisbenzylisoquinoline. The root also contains flavanoids.