1Calyx enlarged towards fruiting stage, either remaining partly free or more or less enveloping the mature fruit.
1'Calyx not enlarged towards fruiting stage.
2Accrescent 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.
3Infructescence fasciculate.
3'Infructescence corymbose-paniculate.
4Enlarged fruit-calyx enveloping the lower half of the fruit.
4'Enlarged fruit-calyx forming a large circular wing.
5Fruit covered by the enlarged disc except the very apex.
5'Disc not enlarged in fruit.
6Epicalyx 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.
7Ramal thorns usually present; leaves more or less deciduous in the dry season.
7'Ramal thorns absent; leaves usually persistent.
8Leaves glabrous.
8'Leaves hairy.
9Leaves 3-5-plinerved; indument of simple hairs.
9'Leaves pinnately veined; indument of branched hairs.