Angraecum sect. Afrangraecum, Summerhayes, 1958

Ječmenica, Vladimir, Droissart, Vincent, Akouangou, Eric, Nyangala, Christelle, Bakita, Bakita, Biteau, Jean Philippe & Stévart, Tariq, 2017, Taxonomy of Atlantic Central African orchids, 6: three new species of Angraecum sect. Afrangraecum (Orchidaceae, Angraecinae) from Gabon and São Tomé, Phytotaxa 323 (2), pp. 143-158 : 147

Key to the 14 species of Angraecum sect. Afrangraecum :

1. Flowers resupinate (lip lowermost)...................................................................................................................................................2.

- Flowers non-resupinate (lip uppermost)............................................................................................................................................8.

2. Lip concave, elliptic, not bent...........................................................................................................................................................3.

- Lip not concave, trullate, strongly bent downwards......................................................................................................... A. angustum

3. Lip subtrilobed; inflorescence determinate, bearing 3 or more simultaneously open flowers..........................................................4.

- Lip entire; inflorescence elongating, indeterminate, bearing one flower at the time........................................................................5.

4. Lip margins undulate; spur slightly sigmoid, 12.0–16.0 mm long; 2 stipites lanceolate, 2 viscidia elliptic........................................ ..................................................................................................................................................... A. firthii Summerhayes (1958: 267)

- Lip margins not undulate; spur ascending, 6.0– 7.5 mm long; 2 stipites ligulate, 2 viscidia lanceolate ........................ A. claessensii

5. Lip elliptic, oblong, narrowly ovate or lanceolate.............................................................................................................................6.

- Lip orbicular......................................................................................................................................................................................7.

6. Lip elliptic to oblong with conspicuous acuminate apex; spur descending, 10 mm long.................................................................... ........................................................................................................................... A. cribbianum Szlachetko & Olszewski (2001: 903)

- Lip narrowly ovate to lanceolate, apex acute; spur straight, 13–15 mm long................................................................... A. oliveirae

7. Leaves broadly elliptic; stem short; pedicel/ovary straight; flowers whitish turning pinkish-orange toward apices .......................... ................................................................................................................................................................................. A. geerinckianum

- Leaves elliptic (oblong); stem elongate; pedicel/ovary curved; flowers pure white................................................... A. gereauanum

8. Inflorescence determinate, bearing one or two flowers.....................................................................................................................9.

- Inflorescence indeterminate, bearing one flower at a time..............................................................................................................10.

9. Leaves up to 17 cm; peduncle to 7 cm; sepals to 30 mm; spur descending, 30 to 53 mm long........................................................... ............................................................................................................................................ A. sanfordii Cribb & Pollard (2002: 653)

- Leaves up to 10 cm; peduncle to 12.5 cm; sepals to 45 mm; spur hanging, 25 mm long.............................................. A. astroarche

10. Sepals longer than 15 mm; spur longer than 25 mm, bent without pronounced apical inflation....................................................11.

- Sepals no longer than 12 mm; spur up to 20 mm, slightly curved, sigmoid or straight with elliptic apical inflation.....................12.

11. Peduncle 2–6 cm; pedicel/ovary 10–13 mm; sepals 15–19 mm; lip 11 × 8 mm, broadly ovate, acuminate with slightly undulate margins; spur length 22–30 mm ............................................................................................ A. mofakoko De Wildeman (1916: 189)

- Peduncle 10–15 cm; pedicel/ovary 15–25 mm; sepals 30–45 mm; lip 30 × 10 mm, narrowly ovate, acute, margins entire; spur length around 70 mm ........................................................................................................................................................ A. reygaertii

12. Lip elliptic; stem internodes> 10 mm .............................................................................................................................................13.

- Lip rhombic (ovate); stem internodes <10 mm ................................................................. A. pyriforme Summerhayes (1936b: 230)

13. Peduncle <2 cm; pedicel/ovary 6.0–8.0 mm; spur straight 11.0–15.0 mm, with a clavate apex ......................... A. multinominatum

- Peduncle <5 cm; pedicel/ovary 9.0– 23.5 mm; spur curved or slightly sigmoid, 13.5–20.0 mm, with an elliptical apex .... A. affine