Adaptive-trait correlations in plant ecology are often calculated among species, but in order to develop and characterize plant materials of target species for restoration, intraspecific comparisons are of greatest relevance. Elymus elymoides (Raf.) Swezey (bottlebrush squirreltail) is an important component of sagebrush-steppe communities in the northern Intermountain West, United States. We evaluated 32 accessions of E. elymoides subspecies C, a newly recognized unnamed taxon, in the field and greenhouse. Our objectives were to assess genetic diversity for putatively adaptive traits, to elucidate biological relationships among biomass, morphological, and phenological traits through correlation analysis, and to gather evidence suggesting whether these traits might be truly adaptive, that is, related to collection-site variables. We observed a positive correlation (r = 0.73;p < 0.01) between greenhouse shoot and root biomass among accessions, suggesting that shoot and root biomass are not in an inherent trade-off relationship across accessions. In addition, accessions with higher greenhouse shoot biomass possessed lower specific leaf area (r = −0.43;p < 0.05) and lower specific root length (r = −0.47,p < 0.05). Correlations between greenhouse and field-measured productivity traits were not significant (p > 0.05), indicating seedling performance is not predictive of mature-plant performance. Elevation was the collection-site variable most closely correlated with plant-measured traits, particularly phenological dates, whereas average annual precipitation was the least significant variable. Therefore, elevation may be used as an easily applied metric to match subspecies C plant material to restoration site in the northern Intermountain West.