Heavy Metal Tolerance in Plants

Publisher Summary This chapter illustrates the literature on those plants and micro-organisms which can combat excessive quantities of heavy metal ions. Heavy metals include those metals which have density greater than five. Their common feature in regard to biological life is that in excessive quantities they are poisonous and can cause death of most living organisms. However, certain organisms possess an ability to survive under conditions of metal contamination which can prove toxic to other living things. Toxic levels of heavy metals can occur under several circumstances. The chapter focuses on the type of contamination in which the soil itself contains large quantities of these metals. The contamination results from the presence of undisturbed metal ore near the soil surface causing anomalies or from the actual mining of ore bodies. The vegetation in such areas is influenced by one overriding factor, namely, metal concentration. The habitats are usually spatially distinct and clear cut. It is observed that the sequence and pattern of genetic change responsible for colonization of metal-contaminated areas serves as a unique record of natural selection in action.