Nickel hyperaccumulation in the serpentine flora of Cuba

Extraordinary uptake (hyperaccumulation) of nickel (Ni), reaching concentra tions of 0.1-5.0%, about 1000-times greater than those usually found in flo wering plants, has been reported over the period 1948-1996 in about 190 spe cies that grow on Ni-rich serpentine soils derived from ultramafic rocks in various parts of the world. A recent study of the families Buxaceae and Eu phorbiaceae identified a further 80 Ni hyperaccumulators from the very larg e ultramafic flora of Cuba, the largest number found to date in any one cou ntry. A much wider investigation of the elemental content of plants from th e Cuban ultramafic flora, reported here with representative analyses of the corresponding soils, has revealed Ni hyperaccumulation in an additional 50 taxa (in 16 genera and eight families). The number of hyperaccumulators is greatest on the oldest serpentine soils, which are believed to have been a vailable for colonization for the last 10-30 million years. Both Ni hyperac cumulators, and serpentine endemic species generally, are much more frequen t on these old soils, occurring in the eastern and western extremities of C uba, than on those developed within the last million years in the central p art of the country. Hyperaccumulating plants of the families Acanthaceae, A steraceae, Clusiaceae, Myrtaceae, Ochnaceae, Oleaceae, Rubiaceae and Tiliac eae are discussed. (C) 1999 Annals of Botany Company.