Riparian ecosystems are highly productive habitats that support a diverse assemblage of vegetation which buffers freshwater bodies, traps sediment, and delivers organic matter to adjacent aquatic systems. These systems are increasingly threatened by soil and freshwater salinization, which can alter plant phytochemistry and reduce species diversity, richness, and evenness and thus the quantity and quality of stream inputs and services. Despite their ecological importance, the effects of salinization across sodium gradients on the phytochemistry and community composition of inland riparian plants remain poorly understood. To address this gap, we conducted a year-long greenhouse paired riparian-stream mesocosm experiment where both systems simultaneously received one of six NaCl addition levels: 100, 200, 300, 400, 500 mg/L NaCl or just water as controls. An additional two treatments were added where just the riparian soil or stream received salt additions (n = 5 replicates per treatment; total N = 40 mesocosms). Salt treatments were added to each mesocosm once weekly. Additionally, we measured soil conductivity, litterfall, plant diversity and height, and leaf chemistry. After ~4 months soil conductivity averaged 73, 78, 149, 117, 192, and 199 uS/cm for controls through 500 mg/L NaCl addition, respectively. Mesocosms had ~56 plant species across all treatments with an average of ~17 per mesocosm. Control treatments had the highest diversity (H’=1.73) and richness (~8) and the 500m/L treatments had the lowest (H’=1.41,~7 respectively). Overall, control treatments were 19% more diverse and ~10% richer than 500 mg L treatments. Litterfall averaged .4994 mg/m-2 across treatments and was highest in the 100mg/L treatments (8520 mg/m-2) and lowest in the 400mg/L treatments (2330 mg/m-2). Litterfall chemistry will be analyzed and discussed. Together these results suggest that salinization may reduce riparian plant diversity and richness. Lower plant diversity combined with alterations to soil conductivity and declines in litterfall rate as salinization increases are likely to alter the quality and quantity of organic matter reaching adjacent streams.