Reynoutria multiflora (syn. Fallopia multiflora and Polygonum multiflorum) is a species of flowering plant in the buckwheat family Polygonaceae native to central and southern China. It is known by the English common names tuber fleeceflower and Chinese (climbing) knotweed. It is known as he shou wu in China and East Asia. Another name for the species is fo-ti, which is a misnomer. The name he shou wu means 'the black-haired Mr. He'.
It can be difficult to prevent the spread of this vining plant and to remove it once established. The leaves are thin and fragile but the stems, although narrow in diameter, can be very strong.