Copper and cobalt in vegetation of Fungurume, Shaba Province, Zaire

The ecology of plant communities over mineralized (copper/cobalt) hillocks at Fungurume, is described. Pteridophytes had a strong resistance to accumulation of these two elements. The vegetation included several endemic ecotypes and ecospecies adapted to high metal concentrations. Uptake of heavy metals was common among succulent species such as Aeolanthus biformifolius. A number of previously unrecorded hyperaccumulators (>1000 μg g-1 dry mass) of copper and cobalt were discovered. These were: Copper - Commelina zigzag and Pandiaka metallorum; cobalt - Anisopappus davyi, Crassula alba, C. vaginata, Cyanotis longifolia, Haumaniastrum homblei, and Sopubia dregeana. Although Crassula alba was a local indicator and accumulator of cobalt it was not confined to mineralized localities. A survey of the heavy metal content of Ipomoea species from the Brussels Herbarium showed accumulation only in I. alpina and I. lukafuensis. A similar survey of eight species of Pandiaka confirmed the very high uptake of cobalt and copper by P. metallorum (up to 6260 μg g-1 Co). This species showed a gradual increase of the cobalt content of its leaves, from 1130 μg g-1 in December to 6260 μg g-1 in April.