| 1 | Fruit subtended by wing-like, enlarged petals. |
| 1' | Fruit usually without wing-like, enlarged petals. |
| 2 | Fruit smooth. |
| 2' | Fruit wrinkled and scurfy |
| 3 | Enlarged petals on the fruit 1-3 cm long. |
| 3' | Enlarged petals on the fruit 5-9 cm long. |
| 4 | Stamens or their scars c. 20-∞. |
| 4' | Stamens or their scars 5 |
| 5 | Leaves pubescent beneath and on the midrib and nerves above. Stamens or their scars ∞ |
| 5' | Leaves glabrous. Stamens or their scars c. 20(-28) |
| 6 | Fruit globose, c. 1½ cm ø. Stamens or their scars ∞ or (8-)10. |
| 6' | Fruit ovoid or ellipsoid, c. 1½ by 1 cm. Stamens or their scars 5 |
| 7 | Stamens or their scars ∞ |
| 7' | Stamens or their scars (8-)10 |
| 8 | Fruit on a centric stalk, globose or subglobose. |
| 8' | Fruit on an excentric stalk (except centric in G. pubescens and G. wrayi), variously shaped, often laterally flattened. |
| 9 | Fruit smooth. |
| 9' | Fruit wrinkled, lenticellate, or scurfy. |
| 10 | Stamens or their scars 5 or 10. |
| 10' | Stamens or their scars many (c. 20-∾). |
| 11 | Stamens or their scars 5. |
| 11' | Stamens or their scars 10 |
| 12 | Leaves 7-13½(-18) cm wide; petiole up to 2 cm. Fruit with a distinct stalk (c. 1-1½ cm); cotyledons free. |
| 12' | Leaves l ¾-4½ cm wide; petiole (2½-)3½-7½ cm. Fruit on an obscure stalk; cotyledons incompletely fused, free on one side |
| 13 | Mature leaves with pubescent midrib on both surfaces; petiole obscure or very short (c. ⅓ cm) |
| 13' | Mature leaves with glabrous midrib on both surfaces. Petiole ¾-2 cm. |
| 14 | Fruit on a stalk ¾-l¾ cm long. Stamens or their scars c. 20(-28) |
| 14' | Fruit on a shorter stalk c. ½ cm long. Stamens or their scars more than 35. |
| 15 | Leaves pubescent beneath, especially on the midrib and veins |
| 15' | Leaves usually glabrous, sometimes pubescent beneath when young, glabrescent |
| 16 | Fruit surface much wrinkled, with irregularly tuberculate ridges, crests, or protuberances. |
| 16' | Fruit surface not wrinkled, but lenticellate or scurfy. |
| 17 | Cotyledons free. Large shrub or small tree up to 10 m high |
| 17' | Cotyledons incompletely fused, free on one side. Tall tree |
| 18 | Fruit densely lenticellate; cotyledons free |
| 18' | Fruit scurfy; cotyledons incompletely fused, free on one side |
| 19 | Fruit smooth. |
| 19' | Fruit scurfy. |
| 20 | Leaves pubescent beneath. Stamens or their scars ∾. Cotyledons free. |
| 20' | Leaves glabrous. Stamens or their scars 5. Cotyledons incompletely fused, free on one side. |
| 21 | Leaf apex acuminate. Free part of the cotyledons 1½-2½ cm deep |
| 21' | Leaf apex rounded, slightly emarginate, rarely cuspidate. Free part of the cotyledons 3-3¼ cm deep |
| 22 | Fruit erect. (Cotyledons incompletely fused, free part ½¾ cm deep; free part/solid part =c. 1: 4) |
| 22' | Fruit not erect but bent obliquely or horizontally. |
| 23 | Petiole usually very short, ¼-¾ cm, sometimes some leaves with petiole up to 1½(-2) cm. Free part of cotyledons c. 1 cm deep (free part/solid part = c. 1: 2-3½). |
| 23' | Petiole 1-5 cm. Free part of cotyledons l½-3¾ cm deep. |
| 24 | Free part of cotyledons 1 ½-2 cm deep (free part/solid part = c. 1: 1-2). |
| 24' | Free part of cotyledons 2¾-3¾ cm deep (free part/solid part = c. 3: 1) |
