NICKEL ACCUMULATING PLANTS FROM THE ANCIENT SERPENTINE SOILS OF CUBA

Extraordinary uptake of nickel (Ni), reaching concentrations of 0.1-5. 0%, c. 1000 times greater than those usually found in flowering plants , has been observed previously in c. 190 species that grow on Ni-rich serpentine soils derived from ultramafic rocks in various parts of the world. These so-called hyperaccumulators of Ni include c. 50 species from the rich ultramafic flora of New Caledonia and c. 80 species from the Brassicaceae of Mediterranean Europe and Turkey. A study of a lim ited part (the families Buxaceae and Euphorbiaceae) of the very large ultramafic flora of Cuba has now identified this as the home of at lea st 80 hyperaccumulators, the largest number yet found in any one count ry. The more frequent incidence here of this unusual form of plant beh aviour is linked to the very long period (c. 10-30 million years) duri ng which some of the Cuban ultramafic substrata are believed to have b een continuously available for colonization; the distribution of Ni hy peraccumulators between older and younger ultramafic soils in Cuba mir rors the overall incidence of endemic species in these areas.