Elemental distribution in Senecio anomalochrous, a Ni hyperaccumulator from South Africa

Senecio sp. aff. S. anomalochrousl/Ig Hilliard (Balkwill 6869 J) Asteraceae, one of five Ni hyperaccumulators in South Africa, was collected from serpentine outcrops near Kaapsehoop Chrysotile Mine (Mpumalanga). Bulk analysis of freeze-dried materials was done by ICP-AES. Studies of two-dimensional elemental distributions were performed using the NAC nuclear microprobe. A gradient of concentrations, increasing from root to leaf, was observed. The highest Ni enrichment was found in the leaf; this is typical of hyperaccumulators. Elemental maps of Ni from leaf cross-sections showed that Ni was present everywhere in the leaf tissue, but in different concentrations. The association of Ni with certain tissues, such as the epidermis, was clearly visible, similar to the trend of Ni concentration in other hyperaccumulators from South Africa, Senecio coronatusl/Ig and Berkheya zeyheril/Ig subsp. lIgrehmaniil/Ig var. rogersiana . The relationships between Ni and other elements were also investigated.