Dipsacus 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 : 58-59

3. Dipsacus L. 1

Stout, biennial herbs, with prickly stems more or less branched above. Leaves opposite, often connate. Capitulum globose to subglobose, ovoid or cylindrical. Involucral bracts in 1-2 rows, linear or lanceolate, erect to patent, with apical spine. Receptacular scales more or less spine-tipped. Involucel more or less 4-angled, united with the ovary below and ending in a short, more or less 4-lobed cup. Calyx cupuliform, ciliate, persistent in fruit. Corolla with a long tube, unequally 4-fid. Achenes 4-angled, appressed-hairy.

1 Cauline leaves shortly petiolate; capitula globose; involucral bracts and receptacular scales similar

2 Capitula 1-5-2 cm; receptacular scales 10-12 mm 7. pilosus 2 Capitula 2-5-4 cm; receptacular scales 15-20 mm 8. strigosus 1 Cauline leaves sessile; capitula subglobose to ovoid or cylindrical; involucral bracts and receptacular scales dissimilar

3 Upper cauline leaves free at base 1. gmelinii 3 Upper cauline leaves connate at base

4Receptacular scales equalling florets, with recurved, rigid apical spine 2. sativus 4At least the lower receptacular scales exceeding florets, with straight or slightly recurved, flexible apical spine

5 Capitula subglobose to ovoid; involucral bracts ±patent or recurved 6. ferox 5 Capitula ovoid-cylindrical; involucral bracts curved upwards

6 Cauline leaves crenate-serrate to entire; involucral bracts linear 3. fullonum

6 Cauline leaves laciniate or pinnatifid; involucral bracts lanceolate-subulate

7 Involucral bracts shorter than florets; receptacular scales ciliate but otherwise glabrous 4. laciniatus

7 Involucral bracts much longer than florets; receptacular scales densely arachnoid-hairy and ciliate 5. comosus