Silybum Adanson

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 : 249

127. Silybum Adanson 1

Robust annual or biennial herbs. Leaves alternate, white-veined or variegated, with strongly spiny margin. Capitula solitary. Involucre ovoid; bracts imbricate, the outer and middle with an apical, setose-dentate appendage terminating (at least in the middle) in a long spine. Receptacle densely hairy. Florets all hermaphrodite. Corolla purple, deeply 5-fid, with a long tube. Achenes obovoid-oblong, compressed, glabrous; pappus of white, scabrid hairs united below into a ring.

Cauline leaves with spines up to 8 mm; outer involucral bracts

with appendage tapering into a recurved spine 1. marianum Cauline leaves with spines 7-15 mm; outer involucral bracts

without a spine 2. ebumeum