Damage done by alien plants

This does NOT refer to Britain as I have no idea about alien plants over here. See http://www.sanparks.org/parks/kruger/conservation/scientific/ff/alien_biota/layout.pdf which si a pdf file.
Most of the plants are very pretty but due to interference by mankind they destroy indigeneous plant life and take over. Over in South Africa the bourganvilla plant is regarded as a pest in the wild and at one time you were paid by the council to destroy the plant as they strangle local plants.
In this case I am referring to KwazuluNatal whish is mentioned quite often in the article. Thought it may be of interest to some and provoke discussion whether we have the same problem over here.

 

I can think of at least one, Giant Hogweed, introduced as a architectural feature plant to Britain in the 19th century...I believe it even won awards at one time!

 

There are a few in Britain. Let's see. Japanese Knotweed, Hottentot fig. Policeman's helmet, ground elder, stinging nettles, Sycamore trees, Crocosmia. You want some more?