T. G. Tutin, V. H. Heywood, N. A. Burges, D. M. Moore, D. H. Valentine, S. M. Walters & D. A. Webb, Flora Europaea 4. 1976
but modified
1Pinnae unlobed; achenes about equalling the inner involucral bracts, rarely longer
1'Pinnae lobed almost to the midrib; achenes longer than the inner involucral bracts
2Leaf-lobes rhombic to broadly lanceolate; pappus-bristles 2-4 mm long, erecto-patent at maturity; outer achenes 8-10 mm long
2'Leaf-lobes mostly linear-lanceolate; pappus-bristles 1-2.5 mm long, erect at maturity; outer achenes 6-8 mm long