Carduus defloratus subsp. glaucus, Nyman

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 : 227

(b) Subsp. glaucus Nyman , Consp. 412 (1879)

( C. crassifolius subsp. glaucus (Nyman) Kazmi , C. glaucus Baumg. , non Cav.):

Leaves entire but spinulose-ciliate with 25-50 pairs of main spines up to 2 mm. Outer and middle involucral bracts contracted at or below the middle into an oblong, obtuse apex; inner twice as long as the inner middle. Achenes with an entire apical prominence. 2л = 22. From C. Germany to the S. Carpathians. Material from the western and southern parts of the range usually has more slender, acute outer and middle involucral bracts. Plants from E. Switzerland, Austria and S. Bavaria, which are probably hybrids between 25(b) and 30 have been called C. viridis A. Kerner , Sched. Fl. Exsicc. Austro-Hung. 1: 74 (1881) (C. defloratus subsp. viridis (A. Kerner) Nyman ). They differ from 25(b) principally in having the leaves with scattered multicellular hairs, the lower and sometimes a few cauline leaves more or less lobed, the outer and middle involucral bracts subulate and distinctly narrower than the inner and the compressed, verruculose achenes. C. rhaeticus (DC.) A. Kerner , Sched. FI. Exsicc. Austro-Hung. 1: 75 (1881) (C. defloratus subsp. rhaeticus (DC.) Rothm. , subsp. tridentinus (Evers) Lad. ), which is common at high altitudes in the C. & E. Alps, is probably a hybrid between 25(a) and 27. It is very spiny, with thick, oblong, more or less lobed leaves, peduncle up to 20 cm, rather obtuse to acute involucral bracts 1-1-5 mm wide and swollen, smooth achenes.