More than 40 years since the discovery of the spectacular New Caledonian hyperaccumulator tree Pycnandra acuminata, knowledge on these unusual plants has advanced considerably. Hundreds of other hyperaccumulators of metal and metalloid elements havesince been reported, and new discoveries continue to be made at anaccelerated pace. The field has matured and is the current subject of detailed investigations into the molecular biology and physiologicalaspects of the hyperaccumulation phenomenon, as well as research on ecological interactions. Hyperaccumulator plants have also found useful applications in phyto-extraction technologies, especially in nickel phytomining.
Much effort in the late 1970s focused onfinding more nickel hyperaccumulators in the Mediterraneanregion and Turkey, in New Caledoniaand elsewhere. To date, 65 hyperaccumulator plantshave been found from New Caledonia, 130from Cuba, and 59 from Turkey, with smaller numbers from Brazil,Malaysia, Indonesia, the Philippines and several other countries. Thesearch is not over: more hyperaccumulators have recently beenfound among herbarium collections using a handheld X-rayfluorescence instrument.The extreme behaviour implied by hyperaccumulation results fromspecific metal or metalloid transport and sequestering mechanisms.Inquiries into these processes span all biological sciences, fromgenetics and molecular biology to physiology and biochemistry.