Strong Accumulators Research Articles

Detection of nickeliferous rocks by analysis of herbarium specimens of indicator plants

Abstract Nearly 2000 herbarium specimens and 232 species of the genera Homalium and Hybanthus were analysed for nickel in order to identify plant accumulators of nickel which were indicative of nickeliferous (usually ultrabasic) rocks. The specimens were originally collected from all parts of the tropical and warm-temperate World between latitudes 40°N and 40°S. They represented a sampling density of about 1 specimen per 2000 km 2 . The survey resulted in the re-identification of all previously known hyperaccumulators (>1000 μg/g on dry-weight basis) of nickel (five species) and in the discovery of five additional species (all from New Caledonia) from these two genera. Fourteen previously unknown strong accumulators (100–1000 μg/g) of nickel were also discovered, most of which were growing over ultrabasic rocks. From the collection localities of the accumulators, it was possible to pinpoint many of the World's major ultrabasic areas in warm temperate and tropical regions. The principle of the method should be applicable to other genera and other elements.