Onopordum acanthium subs. acanthium
Scotch thistle is the national emblem of Scotland. Although it is sometimes cultivated as an ornamental, Scotch thistle is considered to be a noxious weed both in Canada and the United States. Infestations severely degrade rangelands, and dense stands are practically impenetrable because of the spiny nature and large size of the plant. This species has also invaded rangelands in Australia.