Polygonum cuspidatum is a synonym of the accepted name Fallopia japonica. P. cuspidatum, also commonly called Japanese knotweed, is a perennial plant that has hollow stems with distinct raised nodes. It is in the family Polygonaceae, which is widely distributed in Korea, Japan, and China. The dried root is used as a well-known traditional herbal medicine in China and is officially listed in the Chinese Pharmacopoeia. It is also medicinally used in Korea and Japan as a folk medicine to treat diarrhea, cancer, hypertension, dysmenorrhea, coughs, and asthma. The main bioactive compounds of P. cuspidatum root have been identified as emodin, polygonin, and stilbenes (e.g., piceid, resveratroloside, resveratrol). It has been reported that P. cuspidatum has anti-oxidant, anti-inflammatory, wound healing, and anti-bacterial activities.