io6 
F. E. Weiss and R. H. Yapp. 
the northern and southern boundaries of the plain around 
Matjesfontein, exhibit considerable differences, even as seen from 
a distance. Those of the Witteberg range (seen in Fig. 3, PI. V. 
and Fig. 1, PI. VI.), lying to the south, and thus facing the more 
intense northern illumination, are more arid and devoid of vegetation 
than the slopes of the kopjes lying to the north (Fig. 1, PI. V.), and 
thus facing south. 
Unfortunately we were unable to visit the summits of the 
higher and more distant ridges, and had to content ourselves with 
exploring a few of the nearer and lower kopjes. Soil is less 
abundant on these kopjes than on the plain, and bare rock often 
covers much of the surface of the ground. Consequently the 
vegetation is, if possible, still more markedly xerophilous. Thus, 
annuals seemed to be almost entirely absent on the hills, 
while succulents {Aloe, Haworthia, Euphorbia , etc.) became an even 
more prominent feature of the vegetation (Fig. 1, PI. VII.) On one 
of the higher ridges visited (a northern outlier of the Witteberg), 
we found a Restionaceous plant in some abundance. Dr. Marloth 
tells us that the flora of the mountain ridges of this region shows 
some affinity to that of the South-Western region ; as not only 
Restionaceae, but Proteacese and other characteristic Cape forms 
occur on these ridges. 
Of cryptogamic plants, lichens were undoubtedly the most 
conspicuous, the bare rock surfaces on both hills and plain being 
frequently almost covered with patches of lichens: bright red 
{Amphiloma), yellow ( Parmelia ), or grey {Urceolaria, etc.) in colour. 
A few hardy ferns (such as Ceterach capensis, Cheilanthes hirta, 
etc.), some small moss-cushions, and even liverworts were found. 
These appeared to occur most frequently in the more shady and 
sheltered spots, under overhanging rocks, etc., particularly on the 
southern sides of the kopjes. 
In comparison with other desert areas, not only do the presence 
of large numbers of succulents, as well as of bulbous and tuberous 
plants, form a very marked feature of the Karroo, but the systematic 
composition of the phanerogamic vegetation appears to be con¬ 
siderably richer in the Karroo area than in many other deserts. 1 
Bolus* has given a table showing the dominant orders occurring 
in the Karroo region, with the number of species in each. According 
to him there are in all some eighty-four natural orders, represented by 
1 Warming, loc. cit., p. 253, and Schimper, loc. cit., p. 630. 
2 Bolus, loc. cit., p. 225. 
