KEY TO THE GENERA based on fruiting material

1Epicarp crustaceous-verrucose; mesocarp thick, hard, fibrous; endocarp breaking up irregularly on germination; cotyledons at least slightly ruminate.
1'Epicarp smooth and glabrous or distinctly lenticellate but not crustaceous; if lenticellate then endocarp opening by a pair of basal stoppers to allow seedling escape. Cotyledons not ruminate.
2Stamens free to base (can often be seen persistent around base of young fruit). Cotyledons ruminate
2'Stamens united into a unilateral ligule. Cotyledons only slightly ruminate
3Epicarp lenticellate; opening by a pair of basal stoppers to allow seedling escape, always thick and woody; fruit bilocular, but often only one loculus developing seed
3'Epicarp glabrous and smooth without lenticels; opening by lateral plates, longitudinal lines or no special mechanism of seedling escape; fruit uni- or bilocular.
4Endocarp opening by a pair of lateral plates to allow seedling to escape; endocarp thick and woody or thin and bony.
4'Endocarp not opening by lateral plates, usually opening longitudinally; endocarp thin and bony.
5Fruit unilocular; endocarp very thin, bony
5'Fruit bilocular; endocarp thick, woody
6Fruit usually bilocular, 1.5-5 cm long, sometimes sagittate with a distinct stipe, not ridged 4. Hunga b. Fruit unilocular, either 1-1.3 cm long, ellipsoid or 2-5 cm long and ridged.
7Fruit ridged. Leaves orbicular
7'Fruit smooth, not ridged. Leaves oblong to elliptic