The response of two native Arizona plants, fourwing saltbush (Atriplex canescens) and greasewood (Sarcobatus vermiculatus), to five concentrations of nitrate (tap water only, 50 mg/L, 100 mg/L, 750 mg/L, and 2000 mg/L as nitrate) is investigated. Their growth, transpiration, and nitrate and percent nitrogen tissue concentrations were measured. All of the plants' responses were affected by nitrate concentration. In general, it can be concluded that both fourwing saltbush and greasewood tolerated nitrate concentrations as high as 2000 mg/L. However, greasewood's optimal growth was at Level 4 (750 mg/L nitrate) and its tissue nitrate approximately doubled from an average of 572 ± 255 mg/kg at Level 4 to 1020 ± 511 mg/kg at Level 5 (2000 mg/L nitrate). Fourwing saltbush demonstrated a remarkable ability to tolerate large quantities of nitrate and convert it to organic nitrogen at high concentrations. Fourwing saltbush's largest dry mass, 14.48 ± 2.03 g, was at 2000 mg/L of nitrate.