Definition of "knotweed" []

• Any of several plants of the genus Polygonum, with jointed stems and inconspicuous flowers. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Resveratrol comes from grapes (hence the benefit of red wine), peanuts, berries, and a Chinese herb called hu zhang (polygonum cuspidate, also known as giant knotweed, which is a common ingredient in many Chinese herbal formulas)."
• "Some of the "pests" he offers include, Asian shore crabs and Japanese knotweed, which is listed as one of the world's 100 most invasive species."
• "Japanese knotweed, which is native to Japan, Taiwan and China, was introduced by botanists into Britain in the 19th century as an ornamental plant."