The Neotropical genus Galianthe belongs to the tribe Spermacoceae, which constitutes one of the largest herbaceous lineages within the family Rubiaceae. This genus comprises 55 species traditionally divided into two subgenera: G. subg. Galianthe, with 40 species and G. subg. Ebelia, with 15 species; the latter subdivided into G. sect. Galianthe and sect. Laxae. Historically, Galianthe has been morphologically closely associated with the genera Borreria, Diodia, Denscantia, Emmeorhiza, and Spermacoce. However, recent molecular studies have positioned Carajasia and Schwendenera as the phylogenetically most closely related genera to Galianthe. As these previous molecular studies have not covered the full taxonomic, morphological and geographic diversity of all the infrageneric categories of Galianthe, this study aimed to fill these gaps in order to assess the genus' monophyly and explore its inter- and infrageneric phylogenetic relationships. The phylogeny is also used to reconstruct the evolution of some reproductive and vegetative characters mainly related to the taxonomic history of Galianthe. We comprehensively sampled three DNA markers (ETS, ITS, rps16) from 116 accessions, covering 74.541 species) of the current diversity of Galianthe, including 18 closely related genera as well. The Bayesian phylogenetic analyses confirm Carajasia and Schwendenera as successive sister genera of a strongly supported monophyletic Galianthe. The results do not support the recognition of two subgenera. Galianthe subg. Ebelia appears as polyphyletic, split into three different lineages, while all the species of G. subg. Galianthe are recovered in one highly supported group (Galianthe s.str.), with both sections G. sect. Galianthe and sect. Laxae as non-monophyletic. These clades are robustly supported by molecular and morphological data. The replicated evolution of morphological characters suggests an evolutionary convergence towards an adaptive strategy in response to open environments. These results indicate that morphological characters should be interpreted with caution in species delimitation and taxonomic classification, as evolutionary convergence may lead to misinterpretation of phylogenetic relationships.