Health and environmental problems due to contamination are global concerns. Phytoremediation - a biological and sustainable technique - employs plant species to remove, slow down, integrate or decompose certain contaminants to purify soil and water. Our study consisted in contaminating specimens of aquatic macrophyte Hydrocleys nymphoides (Willd.) in the laboratory to test their effectiveness in absorbing and interacting with lead. We analyzed different histological planes of the section and characterized the morphological development of this species. We cultivated 30 plant specimens and 10 control specimens in hydroponic lead acetate solutions at two different concentrations each, 2 and 4 mg.L-1. Statistical analysis revealed that even after contact with lead, specimens grew normally, increasing the number of leaves and flowers. They also presented greater stomatal development and spongy parenchyma thickening, corroborating that this macrophyte can effectively decontaminate water bodies contaminated with lead, constituting a low-cost and ecological alternative.