The taxonomic revision of species of the genus Axonopus P. Beauv. series Suffulti G. A. Black is presented. This series includes perennial species, frequently growing in savannas and in grasslands, on argillaceous or sandy ground with rocky outcrops, at altitudes up to 3500 m. The plants are rhizomatous or stoloniferous, with conduplicate sheaths and narrowly linear to linear-lanceolate blades, flat to folded along their entire length, or open toward the apex. The inflorescences are exserted from the apex of the culms; they consist of spiciform racemes of variable number, mainly digitate. The rachis of each raceme is triquetrous, sinuous, with hispidulous angles, sometimes with long and rigid hairs. The upper lemma and the upper palea are indurate, dark brown, papillose, and shiny. Sixteen species are here considered within Axonopus series Suffulti, principally distributed in South America, with A. ciliatifolius Swallen and A. jeanyae Davidse endemic species of Belize and Panama, respectively. Description of morphological characters and microcharacters of the upper floret, a key to identify the species, descriptions, synonymy, geographical distribution, and illustrations of characters of taxonomic value are given. Finally, lectotypification of series Suffulti is established, and A. ramboi G. A. Black is included in A. argentinus Parodi as a synonym.