The neotropical genus Cybianthus, as here interpreted, contains approximately 150 species in ten subgenera, including the subgenus Grammadenia here proposed. The four objectives of this investigation were: (1) identify the sister genus of Cybianthus and conduct a phylogenetic analysis of its subgenera; (2) analyze the phylogenetic relationships of Grammadenia to determine it generic limits; (3) analyze the phylogenetic relationships of the species in Grammadenia, and (4) test the integrity of character states historically used in the classification of the family by extensive field, laboratory, and herbarium studies. This treatment includes morphological, anatomical, and ecological studies of subgenus Grammadenia along with descriptions, illustrations, and distribution maps.
