Blackberries! I used to go blackberrying and return home scratched from head to foot. Somehow the taste of Mum's blackberry jam made it seem worth the effort.
Another introduced species which must have seemed a good idea, but acclimatised so well as to threaten its host country. Blackberries, foxes, rabbits, prickly pear - the list goes on. Don't even mention the Cane Toad!
My daughter's camellias are particularly beautiful this year.