Semi-aquatic and native plants collected from a mining site in the Iberian Pyrite Belt were analysed. Semi-aquatic plants showed enrichment of Cu (1.2—11 times), Zn (1.3—6 times), Pb (5—8 times) and As (24—1300 times) relative to typical concentrations in plants of the same species growing at uncontaminated sites. Translocation factors indicate limited internal metal transportation from roots to shoots. Infrared spectroscopy identified aromatic and aliphatic C-H (CH2) groups, S-O complexes and kaolinite in semi-aquatic plants.