Carlina acanthifolia subsp. acanthifolia

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 211

(a) Subsp. acanthifolia ( C. utzka Hacq. ): Leaves usually pinnatifid, less than twice as long as wide, sometimes hairy above. Spines on middle involucral bracts mostly branched. Inner involucral bracts straw-coloured. Throughout the range of the species.