Rich sister, poor cousin: Plant diversity and endemism in the Great Winterberg–Amatholes (Great Escarpment, Eastern Cape, South Africa)

• A first comprehensive account of plant biodiversity and endemism in Great Winterberg–Amatholes (GWA), South Africa.
• With 1877 taxa the GWA has a surprisingly richer flora than the adjacent and much larger Sneeuberg.
• The GWA is predictably much poorer than the more distant and massive Drakensberg Alpine Centre.
• Of the 35 endemic plant taxa, five are only known from their types, one is Presumed Extinct, and three are Endangered.
• The results reflect the biodiversity research needs for much of the southern African Great Escarpment.

The Great Winterberg–Amatholes (GWA) is part of the Great Escarpment in southern Africa and ‘sister’ to the Sneeuberg and Stormberg ranges in the Eastern Cape. It comprises a historically well-sampled Amathole Component, and a poorly known Great Winterberg Component. Accordingly, overall plant diversity and endemism have been unknown. Here we define the boundaries of the GWA as an orographic entity and present a comprehensive list of taxa compiled from existing collection records supplemented by intensive fieldwork. With a flora of 1877 taxa, the GWA is surprisingly richer than the adjacent and larger Sneeuberg, but predictably poorer than the very much larger Drakensberg Alpine Centre (DAC). With 1.9% floristic endemism, the GWA could marginally qualify as a new centre of floristic endemism (complimentary to the adjacent Sneeuberg Centre), but formal recognition as a discrete Centre should await comprehensive floristic comparison with the adjacent, poorly studied Stormberg. Due to restricted distributions and pressure from commercial forestry, almost half of the 35 endemics have conservation listings as Rare or stronger, with one Presumed Extinct and three Endangered. Five endemics are still only known from their type specimens. Intensive fieldwork and accurate collation of available data is thus shown as essential for accurate biodiversity assessment and conservation planning in South Africa's montane regions.