100 



to attempt to draw any exact boundary lines on a map, at the 

 present state of our knowledge, is altogether undesirable and 

 only leads to misconceptions. ' 



3.— THE SAM) VELD OF THE KALAHARI AND CENTRAL 



REGION. 



It is well to explain at the outset that the term Kalahari 

 is here used as on the ordinary maps, and not as a name for a 

 large heterogeneous floral region, including half the Free 

 State and the Transvaal, as it was used by Bolus. The Sand 

 Veld (see map) is a definite grassland type which extends 

 from Prieska and Hopetown northwards and westwards all 

 through the Hay district in the valleys, through Griqualand 

 West, Gordonia, Kuruman, Bechuanaland, and the Kalahari, 

 covering altogether an immense area but with singularly 

 uniform ecological conditions throughout it. The rainfall is 

 not very small, varying from 10-20 inches, and increasing 

 froim west to east, but since the whole surface, except in the 

 transitional marginal areas, is covered with sand, there is no 

 surface water and the drainage is underground. The whole 

 area is a great elevated plain, the only mountains being those 

 that surround it, and here and there occasional low elevations 

 of the "inselberg" type. The sand has been blown across from 

 the north-west, and the whole central portion of the area 

 now consists of fixed dunes, which run in a general direction 

 from, north-west to south-east. Towards the margins of the 

 area the sand cover gets shallower, and actual dunes are rarer, 

 but tTie bulk of the country remains sandy. 



The South-Western portions of this area are the driest, 

 and consist chiefly of Aristida Veld with the Toa grass, Aris- 

 tida hrevifolia, dominant. Other Aristidas which serve as 

 pioneers in the establishing of this type are A. congesta, A. 

 hurkei, A. ciliata, A. vestita, A. obtusa, A. uniplumis, A. 

 mollissima, A. stipoides var. meridionalis , A. spinosa. The 

 Zand Kweek grass, Schmidtia hulhosa, is another charac- 

 teristic Sand Veld species. With increasing rainfall towards 

 the Eastern side, this grass veld becomes much more mixed 

 until it merges into ordinary High Veld similar to that of the 

 Transvaal, Free State, and Natal. In addition to those 

 mentioned the following species are recorded : — Andropogon 

 hiriifloTus, A. eucomus, A. hirtus, A. ruprechti, A. schoen- 

 anthus var. versicolor, A. monticola var. tnnii, Imperata 

 arundinacea, Urelytriim sqiiarrosuvi , Elionurus argenteus, 

 Anthistiria imherbis, Panicum trichopiis, P. hohibii, P. 



