Carduus argemone subsp. obtusisquamus, Franco

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 : 227-228

(b) Subsp. obtusisquamus Franco , Bot. Jour. Linn. Soc. 71: 49 (1975)

( C. defloratus auct. gall., non L.):

Leaf-lobules with 3-5 pairs of main spinules; veins slightly raised or indistinct on lower leaf-surface. Outer and middle involucral bracts 1-5-2 mm wide at base, appressed, linear, obtuse, mucronate. Corolla 16-18 mm. Achenes compressed, rugulose. 2л = 22. S.W. Alps and Jura. In the higher parts of the Pyrenees 26(a) and 27 are sympatric and their hybrid has been called C. médius Gouan , Obs. Bot. 62 (1773) ( C. defloratus subsp. médius (Gouan) Bonnier ). It differs from 26(a) in the longer spines (3-7 mm) on stem-wings and leaflobes, shorter peduncle (not more than 20 cm) and the outer and middle involucral bracts with apical spine 1-3 mm.

Plants similar to 26(a) but with involucral bracts of similar shape to 26(b) occur in parts of the Pyrenees and the Cordillera Cantábrica. They have been named C. defloratus prol. medioformis Rouy and require further study. Hybrids between 26(b) and 12,17(a) and 18(b) occur frequently in E. France and W. Switzerland. The hybrid between 26(b) and 5(a) is also found.

C. lobulatus Borbas , Magyar Bot. Lapok 1: 318 (1902), from woods in N.E. Czechoslovakia, looks similar to 26(b). It differs mainly in its narrower (up to 5 mm wide), triangular stem-wings with a spine up to 1 -5 mm, the cauline leaves lobed for i-i(-|) way to the midrib into obtuse or subobtuse lobes with an apical spine up to 1 mm, the peduncle 6-15 cm, with a few small bractlike leaves below, the outer and middle involucral bracts with an obscure mid-vein only in the distal the inner bracts about twice as long as inner middle, and corolla 14-16 mm. Further study is needed to determine its status.