Sediments and rooted aquatic plants are major components of wetland systems. Sediments in these systems act as sinks and reservoirs for organic and inorganic pollutants that are adsorbed to sediment particles or contained in interstitial water that exists between the particle spaces of sediments. Sediments may release toxic materials to aquatic environments through processes that include resuspension, desorption, and bioturbation. In sediment systems, aquatic plants are affected by toxic materials through direct effects on root growth or rhizosphere microorganisms, or by the assimilation and translocation of chemical substances to aerial organs, where they may injure foliage or inhibit growth and seed production. Procedures are being developed to identify the effects of contaminated sediments on aquatic plants through use of laboratory toxicity tests involving natural and artificial sediments, and a group of rooted aquatic species. In these studies, two freshwater species, Echinochloa crusqalli and Sesbania macrocarpa, and a saltmarsh species, Spartina alterniflora, are being evaluated. Artificial substrates proved useful in assessing the effects of contaminants on plant growth and development, and provided techniques for evaluating the role of sediment components on plant response.