The City of Brussels has an active policy in the fight against invasive exotic plants in the city.
Invasive alien species are species originally not present in our surroundings. By their ecological characteristics and extent they form a threat to our native ecosystem. Several of those threatening species currently develop in Brussels:
Black cherry
Giant hogweed
Japanese knotweed
Himalayan Balsam
Brussels also provides a publication, available in Dutch and French, which gives more explanation about these foreign species and shows the best way to combat these alien plants
Brussels
Website