Japanese Knotweed (Fallopia japonica, or You Ji Hu Zhang in Chinese) is native to eastern Asia. It is most famously known for containing high amounts of resveratrol (specifically trans-resveratrol, which is the highest absorbable form). Unlike an extract Japanese Knotweed also contains other beneficial components such as emodin, flavonoids (including rutin and quercetin), oleanolic acid, etc.