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Background and aims Water is the primary limiting factor for plants in drylands, which are projected to become even drier with climate change. Plant functional traits related to water influences individual performance, community composition, and can provide insight into which species will be most vulnerable to drought. Methods Here, we used a trait-based approach to examine key water-related traits of five perennial grasses of the Colorado Plateau, with the goals of identifying functional trait syndromes, and assessing vulnerability to drought. We examined 14 traits including hydraulic, above- and belowground biomass, and morphology, then assessed how these traits varied by species, and photosynthetic pathway. Results Individual water-related traits varied widely, but did not consistently vary by photosynthetic pathway. We identified three unique functional trait syndromes that could be classified as either conservative or non-conservative with regard to water use. Conclusions Variation in water-related traits may be key to the coexistence of species in drylands, but there is uncertainty as which traits or functional trait syndromes will be most vulnerable to changes in climate. Based on the traits examined here, and forecast changes in climate for the region, we predict that the cool-season, C-3 grasses will be most vulnerable in this drying, more drought-prone region.