| 1 | Flowers with a spur longer than 10 cm | 2 |
| 1 | Flowers with a spur shorter than 10 cm | 4 |
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| 2 | Lip smooth at the base, in the mouth of the spur; spur 10-12 cm | Aerangis somalensis |
| 2 | Lip with 2 or more ridges at the base, in the mouth of the spur | 3 |
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| 3 | Lip pandurate (fiddle-shaped); spur with a corkscrew twist; leaves leathery, yellowish green to dark green | Aerangis kotschyana |
| 3 | Lip oblong to obovate; spur straight or wavy but not spirally twisted | 4 |
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| 4 | Leaves succulent, grey-green; flowers November to January | Aerangis verdickii var. verdickii |
| 4 | Leaves dark green; flowers May to June (Rusitu Valley only) | Aerangis verdickii var. rusituensis |
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| 5 | Dorsal sepal 7-13 cm; spur usually 6-8 cm; flowering November or December | Aerangis appendiculata |
| 5 | Dorsal sepal 5-8 cm; spur usually 4-6 cm; flowering March or April | Aerangis mystacidii |
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