Five species of Trillium are recognized as occurring in Texas. One species, Trillium pusillum var. texanum has the major part of its distribution in the state, while another species, T. gracile, is endemic to Louisiana and Texas. Three species, T. ludovicianum, which is reported as new to the state, T. recur vatum, and T. viridescens are considered to be peripheral species. The study, based upon field work and study of herbarium specimens, includes a key to species, partial synonymy, descriptions, specimen citations, and a distribution map of the species.