Fendlera is treated as having five closely related species, four of which have been recognized by previous authors, and F. tamaulipana B. L. Turner, sp. nov., a newly described taxon from northeastern Mexico. Except for the latter, the species are all to some extent sympatric but their populations are relatively uniform and their diagnostic characters do not suggest that intergradation in a populational sense occurs. The taxa do not normally occur together, although they may occur in close proximity and probably do occasionally hybridize, this perhaps confounding taxonomic interpretations of the genus by previous workers. The five species recognized are: F. rupicola, so far as known, confined to three small populations in central Texas; F. falcata, occurring in northwestern Mexico and the southwestern United States; F. wrightii, having a distribution similar to that of the foregoing; F. linearis (including F. rigida), occurring mostly in northeastern Mexico and closely adjacent Trans-Pecos, Texas; and the newly described, F. tamaulipana, known by three collections from the vicinity of Miquihuana, Tamaulipas, Mexico. Distribution maps are provided for all of the species concerned.