Sonchus arvensis, L.

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 : 328

7. S. arvensis L. , Sp. Pl. 793 (1753).

Perennial, far-creeping; stem 30-150 cm, simple or branched. Leaves glabrous, with dentate margins, the lower entire to pinnatipartite with triangular lobes, the upper larger, pinnatipartite to pinnatisect, with round­ ed, often dentate auricles. Capitula terminal, pedunculate. Involucral bracts 38-50. Ligules about as long as corolla-tube. Achenes 2-5-3 -5 x 1-1-5 mm, elliptical, rugose between the ribs; pappus 10-14 mm, persistent. 2л = 36, 54. Cultivated and waste ground, and on maritime sands and shingle. Throughout Europe except for parts of the south-west and some of the islands. Al Au BeBrBuCzDaFaFeGaGeGrHbHeHoHsHuItJuNoPo Rm Rs (N, B, C, W, K, E) Sa Su Tu.

There seems to be no clear correlation in Europe between chromosome number and subspecific differentiation.