Is there a unique serpentine flora on the Witwatersrand?

The flora found on serpentine soils on the Witwatersrand, South Africa, which is only now being studied in detail, superficially appears to be similar to that found on non-serpentine soils. The soils have magnesium to calcium ratios and acidities (pH) similar to the soils of the Barberton Greenstone Belt, but chromium levels are lower and nickel levels are very low. This study compares the Witwatersrand serpentine flora with three non-serpentine nature reserves (Melville Koppies Nature Reserve, Witwatersrand Botanical Garden and Suikerbosrand Nature Reserve). The percentage of exotic flora for each area was also noted. Rare and endangered plants that occur on theWitwatersrand serpentine study sites were recorded and the biome affinities of Witwatersrand serpentine areas were examined. The non-serpentine sites appear to be more similar to the serpentine sites than to each other. There are few exotic taxa present at any of the sites. The serpentine sites on the Witwatersrand are classified as a grassland biome rather than a savanna biome. Three of the taxa that occur on serpentine soils are listed on the Gauteng list of rare and endangered species, but these taxa also occur on non-serpentine soils on the Witwatersrand. No endemic or nickel-hyperaccumulating taxa occur on the serpentine sites on the Witwatersrand. We conclude that the serpentine areas on the Witwatersrand do not support a unique flora.