The Drakensberg Alpine Centre (DAC) comprises the 40,000km 2 high-altitude range of hills, mountain peaks and escarpment plateau bordering the eastern interior of southern Africa. Renowned for its species-rich flora and high levels of endemism, the DAC is here shown to support over 2800 specific and infraspecific native taxa, with c.16% of the angiosperm taxa being endemic, the latter equalling the flora of KwaZulu-Natal. Comparisons of the DAC's largest families and genera are made with those of the Cape Floral Region and KwaZulu-Natal, and the largest families are also compared with those of the Afromontane and Pondoland regions. In addition, comparisons are made between the high-altitude floras of southern and south-central Africa on the basis of their Cape element.

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Plants that lack floral rewards may nevertheless attract pollinators through mimetic resemblance to the flowers of co-occurring rewarding plants. We show how a deceptive orchid (Disa nivea) successfully exploits a reciprocally specialized mutualism between a nectar-producing plant (Zaluzianskya microsiphon) and its long-proboscid fly pollinator (Prosoeca ganglbaueri). Disa nivea is a rare southern African orchid known only from habitats that support large populations of Z. microsiphon, which it closely resembles in both general morphology and floral spectral reflectance. Significant covariation in floral traits of Z. microsiphon and D. nivea was detected among populations. Where mimics are uncommon, flies do not appear to discriminate between the flowers of the two species. Pollination success in D. nivea was much higher at a site with abundant Z. microsiphon plants than at a site where Z. microsiphon was rare. Exploitation of a highly specialized mutualism appears to demand a high degree of phenotypic resemblance to a rewarding model by a deceptive mimic, as exemplified by D. nivea. The majority of deceptive orchids, on the other hand, exploit relatively generalized pollination systems and thus require only a vague resemblance to rewarding plants in the community in order to attract pollinators.

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