Japanese knotweed (Fallopia japonica) forms a dense cover that can crowd out native vegetation. This species can greatly affect the biodiversity in habitats. Photo by: By H. Zell (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)%5D, via Wikimedia Commons
