 Ornithophily is rare and is found in red-flowered species of "Alberta", "Bouvardia", and "Burchellia".Anemophilous species are found in the tribes Anthospermeae and Theligoneae and are characterized by hermaphroditic or unisexual flowers that exhibit a set of specialized features, such as striking sexual dimorphism, increased receptive surface of the stigmas and pendulous anthers.Although most Rubiaceae species are hermaphroditic, outbreeding is promoted through proterandry and spatial isolation of the reproductive organs.