| 1 | Inflorescence of 6 or more pairs of flowers |
| 1' | Inflorescence of 1-4 pairs of flowers |
| 2 | Corolla less than 30 mm long; involucre less than 18 mm long |
| 2' | Corolla more than 60 mm long; involucre more than 50 mm long.... |
| 2'' | Corolla 32-60 mm long; involucre 18-30 mm long |
| 5 | Involucral bracts thin, flexible, acuminate and acute |
| 5' | Involucral bracts rigid, rounded at the apex |
| 3 | Leaf lamina more than 9 cm long; involucral bracts strongly recurved at the apex.. |
| 3' | Leaf lamina less than 9 cm long; involucral bracts not or only slightly recurved at the apex |
| 4 | Stem internodes angular or ridged longitudinally; leaf lamina broadly acute at the apex |
| 4' | Stem internodes terete; leaf lamina obtuse or rounded |
