Technical Abstract: Rangeland plant communities and the hydrologic cycle associated with them are multivariate in nature and are affected by many interacting biotic and abiotic components. A rotating boom rainfall simulator was used to apply rainfall in three applications (dry run, wet run, and very wet run) to paired 3.05 x 10.7 m runoff plots. Representative plant community types were tall-grass, mixed- grass, short-grass prairie, and sagebrush steppe. Indirect gradient analysis was used to summarize relationships between rangeland plant communities and environmental factors. Effective terminal infiltration rate (fe) was highest in sagebrush communities. Comparisons of infiltration equations for the pooled data set (144 runoff plots, 24 sites, 10 states) resulted in fair models (R2=0.45). Infiltration models which represented specific rangeland community types (short-grass, mixed-grass, tall- grass, and sagebrush grass) all had R2 values above 0.71. The use of endemic plant species in the model building process also improved fe rates. For example, in the tall- grass prairie, the inclusion of above ground indiangrass (Sorghastrum nutans) biomass, an endemic grass species, and other plants as independent variables increased model coefficients of determination from 0.71 to 0.83.