| 1 | Calyx enlarged towards fruiting stage, either remaining partly free or more or less enveloping the mature fruit. |
| 1' | Calyx not enlarged towards fruiting stage. |
| 2 | Accrescent calyx almost covering the whole fruit, of which only the umbonate top of the style base remains free. |
| 2' | Accrescent calyx covering the fruit in its basal or lower part, otherwise frill-like expanding and suberect, or expanded and finally reflexed. |
| 3 | Infructescence fasciculate. |
| 3' | Infructescence corymbose-paniculate. |
| 4 | Enlarged fruit-calyx enveloping the lower half of the fruit. |
| 4' | Enlarged fruit-calyx forming a large circular wing. |
| 5 | Fruit covered by the enlarged disc except the very apex. |
| 5' | Disc not enlarged in fruit. |
| 6 | Epicalyx formed by 2 or 3 concrescent bracteoles at the very apex of the pedi- cel, persistent beneath the fruit; calyx practically absent, i.e. adnate to the thick flower-axis. |
| 6' | Epicalyx absent; free calyx present at base of fruit. |
| 7 | Ramal thorns usually present; leaves more or less deciduous in the dry season. |
| 7' | Ramal thorns absent; leaves usually persistent. |
| 8 | Leaves glabrous. |
| 8' | Leaves hairy. |
| 9 | Leaves 3-5-plinerved; indument of simple hairs. |
| 9' | Leaves pinnately veined; indument of branched hairs. |
