126 VEGETATION. 



The rushes in this case perform the part of the hedges, and the 

 moisture rising as dew by night fixes the sand securely among the 

 roots, and a height, instead of a hollow, is the result. While on 

 this subject it may be added that there is no perennial fountain 

 in this part of the country except those that come from beneath 

 the quartzose trap, which constitutes the "filling up" of the ancient 

 valley ; and as the water supply seems to rest on the old silurian 

 schists which form its bottom, it is highly probable that Artesian 

 wells would in several places perform the part which these deep 

 cuttings now do. 



The aspect of this part of the country during most of the year 

 is of a light yellow color ; for some months during the rainy 

 season it is of a pleasant green mixed with yellow. Ranges of 

 hills appear in the west, but east of them we find hundreds of 

 miles of grass-covered plains. Large patches of these flats are 

 covered with white calcareous tufa resting on perfectly horizontal 

 strata of trap. There the vegetation consists of fine grass grow-* 

 ing in tufts among low bushes of the " wait-a-bit" thorn (Acacia 

 detinens), with its annoying fish-hook-like spines. Where these 

 rocks do not appear on the surface, the soil consists of yellow sand 

 and tall, coarse grasses, growing among berry-yielding bushes, 

 named moretloa (Grewia fiavd) and mohatla (Tarchona?itAus), 

 which has enough of aromatic resinous matter to burn brightly, 

 though perfectly green. In more sheltered spots we come on 

 clumps of the white-thorned mimosa (Acacia /wrrida, also A. 

 atomipAylla), and great abundance of wild sage (Salvia Africa- 

 na), and various leguminosse, ixias, and large-flowering bulbs : the 

 Amaryllis toxicaria and A. Brunsvigia multiflora (the former a 

 poisonous bulb) yield in the decayed lamelke a soft, silky down, 

 a good material for stuffing mattresses. 



In some few parts of the country the remains of ancient forests 

 of wild olive-trees (Olea similis) and of the camel-thorn (Acacia 

 giraffe) are still to be met with; but when these are leveled in 

 the proximity of a Bechuana village, no young trees spring up to 

 take their places. This is not because the wood has a growth so 

 slow as not to be appreciable in its increase during the short period 

 that it can be observed by man, which might be supposed from 

 its being so excessively hard ; for having measured a young tree 

 of this species growing in the corner of Mr. Moffat's garden near 



