It consists of trees and shrubs, endemic to the neotropics, with most of the species occurring in the West Indies.

The stamens are inserted near the base of the corolla tube and exserted well beyond its mouth.

[1] Exostema was first named by Christiaan Hendrik Persoon as a subgenus of Cinchona.

[6][7] The generic name is derived from the Ancient Greek words, exo, meaning "outside", and stema, "stamen".

As of March 2023[update], Plants of the World Online accepted the following species:[10]