The endemic Rubiaceae canopy trees of the Comorian Archipelago: floristic affinities in the Indian Ocean and taxonomy. The family Rubiaceae is well represented in the Comoros, but only three species are emergent canopy trees in the humid forest. The first one, Gyrostipula comorensis Homolle ex J.-F.Leroy (tribe Naucleeae) was previously thought to occur on Great Comoro and Moheli, but is now also known from Anjouan, making it an endemic of the whole Union of the Comoros. An emended description is proposed here incorporating data from recent new collections. The two other species belong to the tribe Vanguerieae and are endemic to Mayotte. Peponidium ovato-oblongum (K.Schum.) Mouly, newly combined here, was previously placed under Psychotria, while a later name, Peponidium comorense, here placed under synonymy, has also been published. Pyrostria heliconioides Mouly, newly described here, has spathiform inflorescences, unusual within the genus. These three species, restricted to the Comorian islands, show more affinity to Malagasy than to continental African Rubiaceae.