What are ‘Invasive Plant Species’ Japanese knotweed, Giant hogweed, Himalayan balsam, Rhododendrons, and New Zealand pygmyweed are classified as 'invasive plant species' that can cause issues for both land and structures. Additionally, 'injurious weeds' like some ragworts, thistles, and docks are under strict control. Japanese knotweed, in particular, has been problematic due to its lack of natural predators in the UK. Recently, homebuyers have expressed concerns about the im