Figure 3. Metal hyperaccumulators were believed to have limited potential in the area of phytoremediation owing to their slow growth, low biomass production which limit the speed of metal removal. By definition, a hyperaccumulator must accumulate at least 100 mg g^-1 (0.01% dry wt.), Cd, As and some other trace metals, 1000 mg g^-1 (0.1 dry wt.) Co, Cu, Cr, Ni and Pb and 10,000 mg g^-1 (1% dry wt.) Mn and Ni. Plants that hyperaccumulate metals have other applications and implications. The most important applications are phytoremediation and biogeochemical prospecting. The other implications are elemental allelopathy  and nutrition and toxicology which is of human health related subject.