112 
VEGETATION. 
Chap, VI. 
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 which come from beneath 
the quartzose trap, wliich 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 colour; for some months during the rainy 
season it is of a pleasant green mixed with yellow. Eanges 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 growing 
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 yeUow sand 
and taU coarse grasses growing among berry-yielding bushes, 
named moretloa {G-rewia flava), and mohatla {TarchonantJius), 
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 Jiorrida, also A, 
atomipJiylla), and great abundance of wild sage {Salvia Africana), 
and various leguminosse, ixias, and large-flowering bulbs: the 
Amaryllis toxicaria and A. Brunsvigia multijiora (the former a 
poisonous bulb) yield in the decayed lamellae a soft silky down, a 
good material for stuffing mattrasses. 
In some few parts of the country the remains of ancient forests 
of wild ohve-trees ( Olea similis), and of the camel thorn {Acacia 
giraffe), are still to be met with; but when these are levelled in 
the proximity of a Bechuana village no young trees spring up to 
take their places. This is not because the wood has a gro^vth 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 
