Naturally occurring plants for phytoremediation

Excessive levels of the above metals, that occur in contaminated soils, are generally toxic to most plant species. Only certain plants species and their specific genotypes have the ability to tolerate high concentration of some of these metals (e.g. Ni, Co, Cu, mn, Pb, Zn and Sn). These plants are called hyperaccumulators, and can be used for method of phytoremediation can be classified for convenience into following four technologies : (i) phytoextraction, (ii) rhizofiltration, (iii) phyto-degradation and (iv) phytostabilization.