32 pr];.si])ext's addkkss. 



19. — The Western Littoral or Xamib (Plates XXVIXXVIII). 



Ill striking contrast to the vegetation on the east coast, that 

 on the west is more scanty and desert like than any other part of 

 the sub-continent. This desert region may be described as the 

 \\'estern Littoral or Namib. It reaches from the Olifants Eiver 

 in the south to beyond the limits of our northern boundary. It is 

 a narrow coastal belt, varying in width from 10 to 80 miles, the 

 broadest stretch being from Luderitz Bay to' Conception Bay. 

 It is a barren wind-swept desert composed mainly of vast hills 

 of yellowish sand, and lies west of the western portion of the 

 Great Escai-pment. The rainfall is extremely scanty and varies 

 from to 5 inches per anmmi. 



Some five distinct zones of vegetation may be distinguished,. 

 viz. : that of the western slopes ol the Escarpment, the Gravel 

 Plains, the Sandv Dunes, the ilocky Hills, and the Seashore. 



On the rocky slopes of the Escarpment the Kokerboom 

 (Aloe dichotuma), Eupliorbia virosa, and E. drcgcana are most 

 conspicuous, whilst along the foo-thills clumps of Euphorbia 

 bracliiata are coinmon, and associated with them are plants of 

 the Bushman's Candle (Sarcocaulon Burmanni) and Pelargonium 

 crassicaule, Augea capcnsis, Mesembrianthemtim micranthuni,. 

 Galciiia africana, and Euphorbia namibensis. 



Below this the vast gravel plains are for miles and miles 

 almost destitute of vegetation, or support a more or less scanty 

 growth of Vogelstruis grass [Eragro^fis spinofta). In some 

 places the only plant on these plains is an annual Mesembrian- 

 ihemum, on others nothing but a lichen growth covers the small 

 pebbles. Towards the north only a few isolated plants of Acrva 

 desertonnn occur over vast stretches, while Welwitschia mirabilis 

 is found in a few localities and is usually associated with 

 Zygopliijllum Stapfii. 



The sand dunes support a very scanty vegetation, which is 

 made up chiefly of isolated tufts of Vogelstruis grass (Eragrostia 

 spinosa), Eragrostis cyperoides, the Ganna bush Salsola Zeylieri, 

 Statice scabra and Mesembriantheinum Marlotliii. 



On the rocky hills fringing the seashore the vegetation is 

 more varied, and is composed of many extremely interesting 

 forms, such as Mesembrianthemuni opticvm^ Mcsembrianthonum 

 sa.refauum, M. rliopalophyUutn ^ Trichoraulon cacfifornuty 

 and Euphorbia Jignosa : other common plants are Ectadium 

 virgatum, Ercm.otliamnus Marlofhianus, Dicoma fomenfosa, 

 Pitiiranthus aphiillus, Augea capensis, and Lebeckia muUiflora. 



On' tlie seashore three plants are fairly common, viz. : 

 Salsola zeyheri, CJienolea diffusa and Salicornia natalensis. 



The river valleys which traverse the Namib carry a very 

 typical vegetation. In the upper reaches of the valleys, especially 

 in the north, considerable tree growth occurs, in the dry river 

 beds the characteristic trees are the Anaboom (Acacia albida), the 

 Camel Thorn (Acacia giraffae), the Omumborumbonga (Com- 

 hretiDu primigCHUhi), the Cape Ebony (Eiiclea pseudebenus), the 

 Tamarisk (Tamarix articulata) and the Choris (Salvadora persica). 



The low-lying valleys are practically dominated by vast 

 stretches ol nothing but the Aggennys Euphorbia (E. grcgaria). 



