Water smartweed has alternately arranged, oblong leaves which are about four inches in length. The stem is distinctly jointed with conspicuous membranous stipules that ensheathe the stem at the joints. Smartweed flowers in midsummer with dense pink, rose, or white flowers held erect above the water. The plants may be emergent in shallow water or completely submersed with only the flowers visible above the surface. Smartweed commonly grows in shallow water along shorelines.