| 1 | Perianth segments entire |
| 1' | Perianth segments fimbriate |
| 2 | Usually perennial with strong woody root; inflorescence ebracteate or with small, inconspicuous bracts in the lower half |
| 2' | Usually annual with thin root; inflorescence bracteate with at least the lower bracts similar in size to the cauline leaves |
| 3 | Upper fruit surface convex or flat; perianth segments adpressed to the upper fruit surface |
| 3' | Upper fruit surface depressed; perianth segments erect, incurved at the apex |
