| 1 | Plants herbaceous (or suffrutescent) |
| 1' | Plants woody |
| 2 | Shoot apices deciduous |
| 2' | Shoot apices persistent |
| 3 | Tepals of the pistillate flowers free; stigmas 2, equal |
| 3' | Tepals of the pistillate flowers connate; stigma 1, or if 2, then unequal |
| 4 | Plants armed with curved or straight spines; pistillate inflorescences globose-capitate; tepals and bracts mostly with yellow dye accumulated in immersed glands |
| 4' | Plants unarmed, or if armed, then with straights spines; the pistillate inflorescences not globose-capitate and tepals and bracts without yellow dye containing glands |
| 5 | Plants mostly with thorns or lamina scabrous above; inflorescences spicate or unisexual; tepals of the pistillate flowers (almost) free |
| 5' | Plants without thorns, lamina smooth above; inflorescences cymose if bisexual; tepals of the pistillate flowers connate |
| 6 | Inflorescences bisexual, cymose; tepals of the staminate flowers 4 or 5 |
| 6' | Inflorescences unisexual, spicate; tepals of the staminate flowers 4 or 3 |
