A flora treatment is provided for two tribes of the Rubiaceae subfamily Rubioideae, the Anthospermeae and Rubieae, with identification keys, descriptions of the species (five in Anthospermeae, eleven in Rubieae), data on synonyms, chorology, habitat, vernacular names and uses. Representative herbarium specimens and references to additional literature are given. All this is supplemented with seven detailed drawings and six colour plates to support the identification.
Anthospermum is the only genus of the tribe Anthospermeae occurring in the Democratic Republic of Congo, Rwanda and Burundi. In a recent molecular study, the genus was shown not to be monophyletic, the related genus Nenax being deeply nested within a clade of southern African Anthospermum species. In case of future splitting, the generic name Anthospermum will, however, remain applicable to the species represented in the area covered by this Flora. These are: the widely spread A. herbaceum, A. welwitschii, and A. usambarense. The presence of two further species within the Flora region, A. rosmarinus and A. ternatum, needs to be confirmed.
In Central Africa, the essentially temperate tribe Rubieae is represented by afromontane to afroalpine elements of the genera Rubia and Galium. The first genus is represented by Rubia cordifolia only, while ten species of Galium exist in the Flora region. They are afro(sub)montane (G. bussei, G. chloroionanthum, G. scabrellum, G. scioanum, G. spurium subsp. africanum, G. stenophyllum), afrosubalpine (G. chloroionanthum, G. scabrellum, G. simense, G. thunbergianum) or afroalpine (G. glaciale, G. ruwenzoriense). Unresolved taxonomic issues are mentioned for Galium bussei, G. ruwenzoriense, G. scabrellum and G. spurium.
Recent molecular studies pointed to the need of a future splitting of the large genus Galium. It is not clear at present whether in that case the species dealt with in this Flora will keep their present name under Galium.