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Asiatic knotweed is a thicket-forming herb that can grow to 2m tall. It has zig-zagging stems and red-purple shoots which appear early in spring. As the canes grow, the leaves unfurl and the plant turns green. The mature canes are hollow and have a characteristic pattern of purple speckles. The leaves are long, triangular (15 x 10cm) and pointed at the tip, with a flattened leaf base. In late summer it produces masses of creamy white flowers.
Asiatic knotweed grows primarily in disturbed areas, urban sites, roadsides and along riparian margins. It can tolerate a wide range of soil conditions, high temperatures, high salinity and drought but its growth is depressed by shade.
Asiatic knotweed spreads rapidly, forming dense stands that compete with native vegetation. Its tough shoots and roots can break through gravel, tarmac and concrete; causing damage to foundations, walls, pavements, drainage works, and flood prevention structures. Its dead stems and leaf litter decompose very slowly, forming a deep organic layer and prevents native seeds from germinating. Asiatic knotweed reproduces from seed and can regrow from detached or broken fragments of roots or stems