| 1 | Involucral bracts acute, sagittate |
| 1' | Involucral bracts obtuse to rounded, not sagittate |
| 2 | Leaves long acuminate and acute at the apex |
| 2' | Leaves acute to rounded at the apex but not long acuminate |
| 3 | Young internodes strongly quadrangular; corolla lobes reflexed at 4/5 the corolla height; free part of the filament less than 10 mm long |
| 3' | Young internodes terete; corolla lobes reflexed at 1/2 to 3/5 the corolla height; free part of the filament more than 10 mm long |
| 4 | Involucral bracts spreading widely after anthesis; flowers in the inflorescence 30 or more |
| 4' | Involucral bracts remaining appressed after anthesis, or deciduous; flowers in the inflorescence up to 30 |
| 5 | Anther 4-6 mm long, subsessile on free filament up to 1 mm long |
| 5' | Anther 1.5-10 mm long, longer or shorter than a free filament which is more than 1 mm long |
| 6 | Involucral bracts deciduous after anthesis |
| 6' | Involucral bracts persistent |
| 7 | Flowers and fruits sessile; corolla 35-40 mm long |
| 7' | Flowers pedicellate, the pedicels elongating under the fruits; corolla 23-32 mm long |
| 8 | Involucre less than 30 mm long; corolla less than 30 mm long; anther 1.5-2 mm long, shorter than the free filament |
| 8' | Involucre more than 50 mm long; corolla more than 80 mm long; anther 9-10 mm long, longer than the free filament |
