Included here are the deserts and semi-deserts of the Great Karoo (or Nama Karoo) east of the Western Cape in South Africa and lying at the centre of the South African plateau (or meseta). It also extends over the Orange River into Namibia in the northwest. The Great Escarpment, which runs parallel to the coast 100 km to 200 km inland, divides it into two parts: one between 550 m to 900 m in elevation, the other between 900 and 1300 m.

Bloomkoolganna Veld (Arid Karoo)

This veld type, named after bloomkoolganna the local name for the dominant and also poisonous Salsola tuberculata, is thought to be the climax vegetation of the Arid Karoo. This is the driest part of South Africa with rainfall ranging from just 50-200 mm a year. Most of the Arid Karoo is at an altitude of 900 m but the terrain is extremely flat except along the northern zone of the Roggeveld Mountains where it forms an undulating landscape across the valley of the Sak River. Along the edge of the Orange River it drops to an altitude of about 450 m. Bloomkoolganna Veld is best developed on sandy calcareous tufa mainly found on the northeast and northern borders of the Arid Karoo. It forms a fairly dense growth dominated by Salsola tuberculata and the grasses Stipagrostis ciliata and S. obtusa. Despite the dryness ground cover is surprisingly well developed with short grasses such as Enneapogon desvauxii, Eragrostis nindensis, Ovopetium capensis, Sporobolus lampranthus and Stipagrostis brevifolia predominating. The latter species is said to be the hardiest of all Arid Karoo plants – in severe draught it sheds its leaves and curls up into a yellow-brown ball and can survive when all other plants succumb. Annuals and geophytes are fairly abundant but not very conspicuous. Among the geophytes is the fern Ophiglosssum polyphyllum. Other typical species are Aptosimum spinescens, Dicoma capensis, Eriocephalus spinosus, Hermania spinosa, Lycium oxycladum, Nestleria humilis, Pentzia spinescens, Pteronia glomerata, Rhigozum trichotomum, Ruschia ferox, Salsola glabresens, Sarcocaulon patersonii and Zygophyllum microphyllum. Species of less general occurrence include Acanthopsis hoffmanseggiana, Aizoon schellenbergii, Aptosimum steingroeveri, Berkheya annectens, Geigeria ornativa, Limeum aethiopicum, Lycium arenicolum, Monechma desertorum, Osteospermum armatum, Peliostomum leucorrhizum, Pentzia pinnatisecta, Phaeoptilum spinosum, Plinthus karrooicus, Polygala seminuda, Pteronia leucoclada, Selago minutissima, Tribulus terrestris, Zygophyllum gilfillani and so on. Much of the veld type known as Central Upper Karoo (see below) has now been invaded by Arid Karoo elements due to disturbance from excessive grazing and in places this is now little different from Arid Karoo, and therefore known as False Arid Karoo. 

Central Lower Karoo

This veld type has affinities with Arid Karoo, but situated at lower altitudes (700-1050 m) is not quite as arid. It occupies flat, stony terrain partly on calcareous tufa and partly on stony sandstone and shale. It tends to be shorter and denser than Arid Karoo sometimes having almost complete ground cover. Eberlanzia vulnerans, Pentzia incana and other succulents play an important role, while typical grasses include Stipagrostis ciliata and S. obtusa, both of which are characteristic of Arid Karoo. Other typical species include Aptosimum steingroeveri, Asaemia axillaris, Drosanthemum framesii, Eriocephalus spinescens, Felicia filifolia, Hermannia cuneifolia, Justicia orchioides, Lycium prunus-spinosa, Nestlera conferta, Osteospermum spinescens, Phymaspermum pubescens, Ruschia uncinella, Sphalmanthus tetragonu and Zygophyllum incrustatum. In this dense vegetation very few annuals occur but species of Galenia may be present.

References

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