Buddleia (Buddleija davidii) is a perennial woody species, introduced into the UK in the late 19th Century, which has become rampant in urban environments.
It is known as the Butterfly Bush and continues to be planted in gardens to attract insect life but once it has jumped the wall it can cause havoc. If allowed to develop unchecked it can over run industrial land such as along railways, on development land and derelict plots.
It can spread rapidly, growing anywhere and can be difficult to control unless treated as a specific problem.
Raise your line of sight in any UK city and you can see it growing out of walls and chimneys. Whilst growing in these locations it is not only difficult to access but also degrading the integrity of the surface it is growing on.
Infrastructure maintenance companies have started to take a more proactive approach as the problems that Buddleia causes have been recognised and the cost of remedial measures realised,