Japanese knotweed is a shrub-like perennial that is nicknamed “elephant ear bamboo” and “Mexican bamboo ” because of its bamboo-like stems. It spreads quickly, forming dense thickets that displace native plants and threaten riparian ecosystems. Species Description Japanese knotweed is an upright, shrub-like perennial that can grow to heights of over 13 feet. The leaves are wide, with a heart-shaped base that narrows to a point at the tip. Stems are smooth and hollow resembling bamboo, especially in older plants. Flowers are small and are arranged in clusters of white that appear late in the season. Dead knotweed stems can persist throughout the winter and new shoots, produced from rhizomes, form dense thickets in the spring. The dead stems and leaf litter decompose very slowly and form a deep litter layer which prevents native seeds from germinating. Native & Introduced Range
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