The genus Chaetostoma can be distinguished within the Microlicieae by the combination of the following diagnostic features: keeled, imbricate and pungent leaves lacking glandular punctation; a crown of appressed basally adnate hairs around the outward apex of the hypanthium; tetrasporangiate anthers; mature capsule longer than the hypanthium and reniform seeds with reticulate testa cells. Eleven species are recognized: Chaetostoma albiflorum, C. cupressinum, C. fastigiatum, C. flavum, C. glaziovii, C. inerme, C. armatum, C. riedelianum, C. selagineum, C. scoparium, C. stenocladon. All species of Chaetostoma are subshrubs or rarely shrubs. These species are restricted to a particular vegetational formation, “campo rupestre”, “campo de altitude” and “campo cerrado”, in the Brazilian states of Bahia, Goiás, Mato Grosso, Minas Gerais, São Paulo, Rio de Janeiro and Paraná (Brazil). Chaetostoma armatum has the broadest geographic distribution and the greatest morphological variation.
