Centaurea sterilis subsp. sterilis

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 : 287

(a) Subsp. sterilis (C. stankovii Illarionova): Leaves arachnoidtomentose. Involucre 10-14 x 6-10 mm, ovoid-globose; appendages with narrowly triangular, reddish-brown centre, the apex abruptly contracted into a spine 0-5-2 mm. Achenes 2-5-3-5 mm; pappus 0-5-2 mm. S. & S.E. Krym.