Carduus bourgeanus subsp. bourgeanus

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 : 230

(a) Subsp. bourgeanus :

Wings of stem and spines of leaves up to 5 mm. Capitula 3-7 together at the apex of branches. Outer and middle involucral bracts with an apical spine 1-2 mm, glabrous or almost so; inner bracts twice as long as the outer. Almost throughout the range of the species.