THE PLANT EC0LO(iV OF DRAKENSBERG RANGE. 531 



we have certain striking differences in the genei'al appear- 

 ance and ecology, as well as in the composition of this 

 mountain veld. Nowhere do we find the large associations 

 dominated by a single species, which are common in the 

 Midlands. The Anthistiria association, which covers so 

 much of Natal, is not extensive. The Andropogon asso- 

 ciations are fairly comuKni, but not so characteristic of every 

 hillside as at lower altitudes. 



The Tambootie association (Andropogon nardus var. 

 marginatus) is well developed in certain places, e.g. in the 

 valley of the Tugela around Groodoo. Certain of the species 

 characteristic of the Zwart Kop mountain, near l^ietermaritz- 

 burg, — a type already described by the writer — assume a 

 much greater importance on the Drakensberg. 



The task of determining the exact requirements of each 

 species represented would require a long and careful study 

 in the field, and, consequently, a prolonged residence on the 

 Di-akensberg. 



Though stress shoukl be laid on the soil conditions in 

 determining the relationship of the species composing the 

 Alpine veld to one another, and in determining further the 

 relationship of the veld to the other plant formations of the 

 area, yet probably the explanation of the difference between 

 this veld and that of lower altitudes is to be found rather in 

 the climatic factors — the stronger insolation and its effect on 

 soil temperatures ; the rarefaction of the ai]- and its greater 

 dryness and the increased evaporation at certain seasons; 

 the lowering of the temperature and increased radiation, etc. 



In reaction to these conditions, we find the following 

 features of Alpine veld : 



(a) The grasses grow more in tufts and tussocks, the 

 different culms thus affording one another greater mutual 

 protection. There are bare spaces between the tufts. This 

 gives the veld a characteristic appearance, very different 

 from that of the Anthistiria veld of lower altitudes, which 

 has a uniform, even appearance in late summer, like a culti- 

 vated field of rye-grass. 



