Onopordum

Some species of Onopordum have been introduced as ornamental plants in the temperate regions of North America and Australia, where they have become naturalised in the wild. In most of these countries, these thistles are considered noxious weeds, especially in Australia where a biological control program has been set up (using the Rosette Crown Weevil, Trichosirocalus briesei). In North America, there are also Trichosirocalus control programs, but they have proved detrimental to native thistles. == References==