Phosphorus (P) losses from agricultural landscapes contribute significantly to eutrophication of surface waters. The total amount of P absorbed by plants growing in or near grass filter strips and riparian buffers can be determined, but we have little knowledge of the pattern of accumulation/depletion during the course of a growing season, nor do we understand how plants respond to influxes of dissolved P that occur after rainfall events. In this study, we evaluated P acquisition efficiency of switchgrass (Panicum virgatum L.), smooth bromegrass (Bromus inermis Leyss.) and reed canarygrass (Phalaris arundinacea L.) grown in a flowing nutrient solution culture system at mean solution P concentrations of 1 and 100 µmol L^-1. Plants were harvested four times. Changes in shoot and root growth, P influx, and P uptake kinetics were determined, and species differences compared.