The overall likelihood of H. scandens continuing to enter the EPPO region along the pathway plants for planting is moderate as the species is cultivated and traded within the EPPO region. The risk of the species being introduced into other EPPO countries is considered high as the plant is traded both within the region and to a lesser extent into the EPPO region from outside. In addition, natural spread by river systems will also facilitate its spread between countries (for example the Danube River system).