Xanthium strumarium subsp. strumarium

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 : 143

(a) Subsp. strumarium :

Not aromatic. Stems and branches green. Involucre 12-15x 6-10 mm in fruit, green or greyish-green when ripe, covered with dense but slender spines. 2n- 36. Throughout the range of the species", native.