Ultramafic Substrates Research Articles

ACCUMULATION OF NICKEL BY PSYCHOTRIA SPECIES FROM THE PACIFIC BASIN

SummaryThirty‐two Psychotria species from New Caledonia and 178 from other islands of the Pacific Basin were analyzed for nickel in order to identify hyperaccumulators (> 1000 μg/g dry mass) of nickel. P. douarrei was the only taxon which possessed this character and contained a mean concentration of 2.24% nickel in its leaves. This is higher than for any other known hyperaccumulator of nickel. Pot trials showed that P. douarrei can grow in substrates containing up to 1% plant‐available nickel. It is suggested that P. dourarrei is a neoendemic taxon possibly derived from P. baillonii which occupies complementary ecological niches on non‐nickeliferous soils adjacent to the ultramafic substrates supporting P. douarrei. Evolution may have proceeded via an intermediate nickel‐tolerant ecotype of P. baillonii which can still be found growing in association with P. douarrei.