Mitriostigma (Hochst.)

Sonke´, Bonaventure, Simo, Murielle & Dessein, Steven, 2009, Synopsis of the genus Mitriostigma (Rubiaceae) with a new monocaulous species from south Cameroon, Nordic Journal of Botany 27, pp. 305-312 : 309

Key to the species of Mitriostigma

1. Monocaulous (i.e. single-stemmed) dwarf; inflorescences supra-axillary and paired at the nodes (Cameroon) ....... ................................................................. M. monocaule

1. Trees, shrubs or sub-shrubs; inflorescences placed unilaterally at successive nodes on alternate sides, sometimes axillary at the nodes (Africa, also Cameroon) ............. 2

2. Length of corolla lobes 1/3-1/2 of length of corolla tube ............................................................................. 3

2. Length of corolla lobes less than 1/3 of length of corolla tube ............................................................................. 4

3. Leaves elliptic to ovate; inflorescences placed unilaterally at successive nodes on alternate sides ........... M. axillare

3. Leaves obovate; inflorescences usually paired at the nodes ......................................................... M. greenwayi

4. Inflorescences supra-axillary; corolla tube ca 24 mm long; fruits 22-25× 14-16 mm, ellipsoid (Tanzania) ............ ............................................................... M. usambarense

4. Inflorescences axillary; corolla tube 9-14 mm long; fruits 25-40× 8-15 mm, sub-fusiform (Cameroon, Bioko) ... ....................................................................... M. barteri