Centaurea schousboei subsp. schousboei

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 : 276

(a) Subsp. schousboei :

Involucre 6-9 mm in diameter, tapering at base; appendages with 6-9 brown fimbriae on each side, the apical spine 1 mm. Almost throughout the range of the species.