Included here is the Namib Desert in southwest Africa. It represents an extremely arid coastal strip roughly extending from Benguela south to the mouth of the Orange River just south of Alexander Bay.
Namibian Sand Dunes
In large parts of the Namib, especially in the south, there are large shifting dunes up to 300 m high and largely devoid of vegetation. The main species able to tolerate these conditions are Eragrostis cyperoides, Stipagrostis sabulicola and the endemic Stipagrostis gonatostachys (Poaceae). On smaller dunes endemics such as the strange spiny shrub Acanthosicyos horrida (Cucurbitaceae) and the endemic Trianthema heteroensis may be present together with Psilocaulon marlothii. In the slightly wetter areas Limeum fenestratum and Stipagrostis lutesens become the more important species. On the more compact substrates Galenia africana, Pterodiscus aurantiacus, Sesuvium portulacastrum, Vogelia africana, Zygophyllum orbiculatum, Z. simplex, the endemic Stipagrostis subacaulis (Poaceae)and occasionally the near endemic Welwitschia mirabilis (Welwitschiaceae) are some of the species encountered.
Namibian Sandy Plains
These have been divided into several communities depending on the amount of moisture available. In the moist foggy zone the endemic Arthraerua leubnitziae (Amaranthaceae) is one of the dominant species and is particularly conspicuous on gypsum plains, while in the dryer areas Salsola tuberculata and Stipagrostis ciliata or S. obtusa predominate. Two of the more spectacular formations associated with this habitat are the Welwitschia and Teloschistes plains. In certain areas, such as in the vicinity of the Swakop River, the bizarre near endemic gymnosperm Welwitschia mirabilis (Welwitschiaceae)completely dominates the vegetation. It tends to follows underground watercourses. Equally bizarre is the orange fructicose or shrubby lichen Teloschistes flavicans, which together with other lichens such as Parmelia convoluta and various species of Usnea, dominated some of the coastal plains.
References
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