102 

 4.— THE KARROO AND KARROID CENTRAL REGION. 



This region lias a dry continental type of climate, the 

 average rainfall for different parts varying between 8 and 14 

 inches. On the south western side it is bounded by the region 

 of Macchia already described. On the east, it grades into 

 Grassveld, the approximate boundaries of which are given 

 later, when the transitional belt between the two is dealt with. 

 On the north, it grades into Sand Veld, the boundary being 

 a wide curve from Hopetown to Prieska, and thence southward 

 to Carnarvon. Still further west through Kenhart, Calvinia, 

 and Bushmanlaud, there are many areas of Karroo, but the 

 whole of this area must be considered transitional to the 

 desert types of the west, much of it consisting- of red sandy 

 flats and sand hills. In this western transitional area, one of 

 the most important grasses is the Vogelstruis or Ostrich grass, 

 E hi y vost is spinosa. Drege describes it as covering vast tracts, 

 and Burchell in his "Travels" (1810-15) refers to it as fol- 

 lows. The quotation is worth giving at length. "I now" 

 (at the Little Thorn Biver) "gathered for the first time speci- 

 mens of a very extraordinary grass. Its panicle of flowers 

 formed a bunch of strong sharp thorns, so rigid and pungent 

 that no animal could graze near it, nor would the naked 

 legged Hottentots venture to walk among it, although it was 

 not more than a foot and a half high." The Toa grass, 

 Aristida brevi folia, may also be described as covering vast 

 tracts in the same region. It is a suffrutescent species. Other 

 species of Aristida [A. obtusa, A. vc.stita, A. ciliata, A. uni- 

 plumis, A. namaquensis) are also common, and show the close 

 connection with the Western region. Stipa tortilis is another 

 characteristic species. 



In the Karroo proper, the dominant vegetation is of a 

 succulent and sclerophyllous dwarf shrub type, made up of 

 Crassulaceae, Aizoaceae (MesembrianihemuTn), Compositae, 

 .and many other orders. The Compositae increase in import- 

 ance towards the north. Penizia virgata (Karroo bush) is 

 dominant over wide stretches. 



As far as the actual number of species is concerned, the 

 grasses are fairly well represented, but very few of them can 

 be considered as specially of a Karroo type, and they are of 

 comparatively little importance in the climax stages of the 

 succession on the typical Karroo flats. They are confined for 

 "the most part to the dongas or ravines, and stream beds, or 



