Another genus of small-leaved succulent Rubiaceae found near the sea coast in our region is Phylohydrax. Dessein et al. (2005) documented the morphology, anatomy, biology, and distribution of both of these genera. They also demonstrated that Phylohydrax and Gomphocalyx are closely related to each other and also to genera that have been included in Hedyotideae, rather than the genera of Spermacoceae s. str. where these genera have usually been classified. See Phylohydrax for a key to separate these genera.