A hyperaccumulator is a plant capable of growing in soils with very high concentrations of metals, absorbing these metals through their roots, and concentrating extremely high levels of metals in their tissues. The metals are concentrated at levels that are toxic to closely related species not adapted to growing on the metalliferous soils. Compared to non-hyperaccumulating species, hyperaccumulator roots extract the metal from the soil at a higher rate, transfer it more quickly to their shoots, and store large amounts in leaves and roots. The ability to hyperaccumulate toxic metals compared to related species has been shown to be due to differential gene expression and regulation of the same genes in both plants. Over 500 species of flowering plants have been identified as having the ability to hyperaccumulate metals in their tissues.
Hyperaccumulating plants hold interest for their ability to extract metals from the soils of contaminated sites (phytoremediation) to return the ecosystem to a less toxic state. The plants also hold potential to be used to mine metals from soils with very high concentrations (phytomining) by growing the plants then harvesting them for the metals in their tissues.
The genetic advantage of hyperaccumulation of metals may be that the toxic levels of heavy metals in leaves deter herbivores or increase the toxicity of other anti-herbivory metabolites.