Marsdenia (Brown, 1810)

Juárez-Jaimes, B. Verónica & Lozada-Pérez, Lucio, 2015, Marsdenia microcarpa, a new species of Marsdenia (Apocynaceae, Asclepiadoideae) from montane Guerrero, Mexico, Phytotaxa 217 (1), pp. 92-95 : 94

Key of the species of Marsdenia in the state of Guerrero

1 Leaf blades oblong to oblong-ovate...................................................................................................................................................2

- Leaf blades elliptical, ovate to suborbicular.......................................................................................................................................3

2 Leaf blades without colleters at the base of the middle nerve; inflorescences congested-paniculiform, peduncle 1–2 mm long; corolla campanulate, purple to blackish, with a fleshy callus below the sinuses............................................................... M. mayana

- Leaf blades with colleters at the base of the middle nerve; inflorescences loosely paniculiform, peduncle 15–25 mm long; corolla urceolate, white, without a fleshy callus below the sinuses ......................................................................................... M. microcarpa

3 Gynostegial corona absent.................................................................................................................................................... M. lanata

- Gynostegial corona present................................................................................................................................................................4

4 Inflorescences umbelliform................................................................................................................................................................5

- Inflorescences paniculiform or racemiform.......................................................................................................................................7

5 Corolla without a fleshy callus in the petal sinuses; tube 3–4.2 mm long ................................................................... M. zimapanica

- Corolla with a fleshy callus in the petal sinuses; tube up to 2.3 mm long.........................................................................................6

6 Flowers creamy white; callus pubescent; corona lobes sagittate; style-head appendix conical-rounded, apex obtuse, not bifid ....... ............................................................................................................................................................................................. M. callosa

- Flowers white with red or purple lines; callus glabrous; corona lobes rounded to obtuse; style-head appendix attenuated, apex deeply bifid................................................................................................................................................................... M. trivirgulata

7 Inflorescences racemiform; corolla tubular.................................................................................................................... M. propinqua

- Inflorescences paniculiform; corolla urceolate to campanulate.........................................................................................................8

8 Inflorescences 1 per node, peduncles 3–7 mm long; corolla urceolate................................................................... M. astephanoides

- Inflorescences 2 per node, peduncles 20–25 mm long; corolla campanulate ................................................................. M. mexicana