Long cult. as the fullers' teasel, is rarely adventive with us. It differs from the closely allied wild D. sylvestris in the stouter, strongly recurved spine-tips of its receptacular bracts. Linnaeus included both in his D. fullonum, and the name has subsequently been restricted by different authors to each of them.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.