Three new species of Vanguerieae (Rubiaceae) from Madagascar

Three new species of the tribe Vanguerieae (Rubiaceae) from Madagascar are described with illustrations. Two species are placed in Pyrostria, one in Peponidium. Peponidium crassifolium is recognized by its thick and slightly succulent leaves, Pyrostria pendula by the pendulous flowers and persistent pedicels, and Pyrostria serpentina by a serpentine habit and small leaves. The morphology and taxonomic history of the dioecious genera of the tribe are discussed.