Crusty gypsum exposures are scattered throughout the Trans-Pecos (Fig. 4), often near the saline habitats, and characteristic assemblages of plants are restricted to these areas, for example Tiquilia hispidissima, Gaillardia multiceps, Gypgrass (Sporobolus nealleyi), Selinocarpus spp., and Anulocaulis spp. (Powell and Turner, 1977).