ENDEMIC FLORA OF THE NORTH-EASTERN TRANSVAAL ESCARPMENT, SOUTH-AFRICA

The endemic seed plant flora of the north-eastern Transvaal Escarpment (part of the Afromontane Region) is assessed in terms of the region's lithology (mainly rocks of the Transvaal Sequence). A total of 81 species and infraspecific taxa are endemic or near-endemic to the quartzitic and related rock types of the Black Reef Quartzite Formation, Wolkberg Group and Timeball Hill Formation (c. 3880 kM2) and a total of 32 species were recorded as endemic or near-endemic to the dolomitic Chuniespoort Formation (c. 2100 kM2). As a major centre of biodiversity, we propose to name this escarpment region of Transvaal Sequence, the Wolkberg Centre. Two subunits of endemism are recognized: the Blyde Subcentre in the south, and the Serala Subcentre in the north. Although the number of endemics on dolomite is less than half the number on quartzite-derived substrates, the degree of endemism is higher on the former. The majority of dolomite endemics are confined to the drier areas and are not of such strong Afromontane affinity as the quartzite ones. Nearly all the endemics are herbaceous, conforming to the observation that regional endemism levels in the Afromontane Region are high in grassland, but low among the tree flora of the patches of undifferentiated evergreen forest. The vegetation of the Wolkberg Centre, especially the grasslands, is under considerable pressure, particularly from the timber industry and invasive alien plants. Existing and proposed conservation areas in the centre are listed.