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Mexican feathergrass (Nassella tenuissima (Trin.) Barkworth) is a C 3 bunchgrass native to the Trans-Pecos region of West Texas and south-central New Mexico in the United States but has been planted as an ornamental in many other regions. N. tenuissima can escape from landscaping areas and become a weedy species on disturbed rangelands. To understand any physiological advantages this species may over native species, we surveyed three N. tenuissima colonies throughout a remnant 54-ha native shortgrass prairie within the limits of Lubbock, Texas, USA in the summer of 2022. We selected N. tenuissima from three locations within the colonies: inner, edge, and outer for physiological (i.e., leaf-level gas exchange) and morphological (i.e., basal area) measurements. We also monitored two 'companion' native grasses adjacent to N. tenuissima in the outer location: blue grama (Bouteloua gracilis (Kunth) Lag. ex Griffiths) and purple threeawn (Aristida purpurea Nutt.). N. tenuissima photosynthesis rates were greater than those of A. purpurea and B. gracilis, while stomatal conductance and transpiration rates were similar among species. No significant differences were seen in photosynthesis, stomatal conductance, or transpiration rates across the three colony locations for N. tenuissima. N. tenuissima cover and biomass was greatest in inner locations and decreased with distance away from the center of colonies. In contrast, warm-season grass and forb cover increased with distance away from the center of colonies. N. tenuissima appears to exhibit physiological and morphological advantages over native warm-season grasses, which likely contribute to its expansion in the local region, particularly at degraded and overgrazed sites.