ZINC, LEAD AND COPPER TOLERANCE IN THE GRASS <i>STEREOCHLAENA CAMERONII</i> (STAPF) CLAYTON

Abstract

SUMMARY Stereochlaena cameronii , a grass widely distributed in south central Africa, possesses tolerance towards heavy metals. Its tolerance and accumulation of zinc, lead, copper, iron, manganese and magnesium as well as sulphur have been studied and compared with similar phenomena in two other local metal‐tolerant grasses, Cynodon dactylon and Trachypogon spicatus , as well as in some herbs and trees. The grasses accumulate high levels of copper in their roots in contrast with the herbaceous plants which accumulate the metal in their leaves. Distribution of other metals between roots and leaves is variable and is related to soil composition. Heavy‐metal tolerance in Stereochlaena cameronii does not appear to be dependent directly on sulphur or nitrogen metabolism. In S. cameronii from zinc‐rich soil, the zinc is largely in insoluble form in the roots, but in plants from other soils about half of this metal is in soluble form.