| 1 | Corolla more than 15 mm long |
| 1' | Corolla less than 13 mm long |
| 2 | Pedicels flattened, winged and widened upwards; corolla 6-merous.. |
| 2' | Pedicels angular but not flattened or winged; corolla 5-merous |
| 3 | Pedicel shorter than ovary; inflorescence axis 20-60 mm long |
| 3' | Pedicel mostly longer than the ovary; inflorescence axis 50-250 mm long |
| 4 | Style reaching to the top of the anthers; inflorescence axis less than 70 and often less than 50 mm long |
| 4' | Style reaching only to near the base of the anthers; inflorescence axis more than 60 and often more than 100 mm long |
| 5 | Flowers sessile; petals commonly 5, sometimes 4 |
| 5' | Flowers pedicellate, sometimes very shortly; petals 4 |
| 6 | Leaves rounded at the apex; inflorescence axis up to 40 mm long; corolla rounded in bud, 3.5-5 mm long; anther shorter than the free filament |
| 6' | Leaves acute at the apex; inflorescence axis more than 45 mm long; corolla acute in bud, 5-7 mm long; anther longer than the free filament |
| 7 | Inflorescence of 10-30 flowers distributed along an axis 15-70 mm long; free filament longer than the anther |
| 7' | Inflorescence of 2-5 flowers subumbellately crowded near the tip of an axis 5-20 mm long; free filament much shorter than the anther |
| 8 | Style angular in the lower part below a constriction near the middle, more slender above |
| 8' | Style terete or angular, gradually widened upwards, lacking a constriction.... |
| 9 | Flowers sessile; bracts strongly reflexed, with a dorsal spur-like sac; style weakly constricted |
| 9' | Flowers pedicellate, sometimes very shortly; bracts not strongly reflexed, sometimes with a dorsal transverse fold but lacking a sac; style strongly constricted.. |
| 10 | Inflorescence sometimes subtended by an involucre of a few narrow bracts up to 5 mm long; ovary barrel-shaped or shortly cylindric, usually with irregular wrinkles or furrows persisting to the young fruit; corolla 3.5-8.5 mm long |
| 10' | Inflorescence subtended by an involucre of numerous linear bracts up to 15 mm long; ovary cylindric, longer than wide, usually slightly narrowed below the calyx limb, sometimes longitudinally weakly angled or furrowed; corolla 7-12 mm long |
