Interactions of plants with metals and metalloids have attracted considerable attention in recent years (Merian 1991; Prasad 1996). This interest has been for a number of different reasons, reflecting the variety of areas of the importance of plants and the different roles played by the different elements. Indeed, whereas many elements (e.g. B, Se) are well-established essential nutrients for plant growth, others (e.g. Cd, Pb) are well-recognized stress factors. Plants produce edible fruits and vegetables that are important (and sometimes major) sources of trace elements in the human diet that makes legislation set limits regarding toxic metal concentrations. Tea, coffee and wine are important sources of trace elements in the human diet in some countries. Selenium-enriched plants are increasingly used in medicine and as food supplements. The use of specially engineered plants has been attracting growing interest in the remediation of polluted waters and soils (phytoremediation). For some elements, especially As, plants (e.g. algae, seaweeds, and phytoplankton) are an important link in food chains.