Apocynaceae (oleander, frangipani, periwinkle, milkweed and asclepiad family)

About 415 genera and 4555 species, native mainly to tropical and warm temperate regions, with 82 genera and 675 species native to southern Africa, an additional 5 genera and 6 species naturalised, and an additional 19 genera and 58 species that are cultivated in the region.

Gelsemiaceae

Two genera and 11 species, native to South East Asia, America and Africa but not to southern Africa. However, Gelsemium rankinii (Yellow jessamine) (native to the southeastern USA) is cultivated in the region.

Gentianaceae (gentians)

About 87 genera and 1655 species, with a nearly worldwide distribution. Nine genera and 71 species are native to southern Africa, there are no naturalised species, and a further four genera and 11 species are cultivated in the region.

Loganiaceae (strychnine family)

Worldwide there are 29 genera and about 600 species in this family. The only genus native to southern Africa is Strychnos (with 10 species native to the region) sometimes placed, together with two other genera, in a separate family, the Strychnaceae. 

Rubiaceae (gardenia, coffee and quinine family)

A large family of 630 genera and about 10200 species found worldwide but particularly in tropical and warm regions. Fifty-nine genera and 233 species are native to southern Africa, an additional three genera and 6 species are naturalised, and an additional 19 genera and 47 species that are cultivated in the region.