Fallopia x bohemicum
[Bohemian Knotweed]

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At least one website had named this plant as Polygonum runcinatum (Chinese name: 赤胫散). In a Chinese herbal remedy book published in Malaysia (马来西亚生草药实用小秘方, volume 3, page 21), the same name was used. However, this plant is unlikely to be Polygonum runcinatum (Lobed Leaf Knotweed).