Catalogue › FlowersCottonthistle (Onopordum)Every species of the genus Onopordum in the catalogue.Cotton Thistle (Onopordum acanthium)Stemless thistle (Onopordum acaulon)Illyrian cottonthistle (Onopordum illyricum)Bull cottonthistle (Onopordum tauricum)Woolly-headed cotton thistle (Onopordum eriocephalum)Bristly cotton thistle (Onopordum horridum)