THE VEGETATION OF NATAL. 309 



difference is greatest in the undergrowth. Near tlie water-edge 

 on the steep rocky banks an interesting and varied Crypto- 

 gamic flora is found. Such a spot is illustrated in PI. XVII, 

 fig. 1. In addition to various ferns and Selaginellas 

 and Streptocarpus spp., mosses and hepatics cover the 

 faces of the rocks and fill the chinks. From the spot illustrated 

 a number of hepatics were sent to Dr. W. H. Lang, who 

 identified species belonging to the genera Fimbriaria, 

 Duma r tier a, Riccia, Aneura and Anthoceros. 



In the Sweet waters Bush, which is illustrated in PI. XVI, 

 Rauwolfia natalensis is the dominant tree. In other 

 similar bushes one or other of the species mentioned may be 

 dominant. So the type is more variable and indefinite than 

 that found on the south-eastern slopes,^ 



The various types of bush described so far all show a very 

 definite relationship to the different factors. They grow in 

 the places where there is maximum deposition of moisture ; 

 they require a well-drained, well-aerated soil which may be, 

 and in fact usually is, somewhat rocky ; they do not require 

 to withstand strong frosts ; they are sheltered from the hot 

 dry winds. It is fi'om fires that they suffer most, and these 

 are gradually eating into them, and in the past a considerable 

 amount of bush has been destroyed by this means. This close 

 type of bush is associated with the high level grassland to 

 form the Bush Veld or Bosh Savannah or Forest Savannah. 



(9) THORN VELD. 



In reaction to the very different conditions found at the 

 low dry valley levels we get the Thorn Veld or Thorn 

 Savannah. The trees are scattered through the veld grasses, 

 and rarely grow close together. They present a sort of 

 park-like aspect. Before discussing their form and relation- 

 ships I will give a list of those that commonly occur. 



' Dr. W. G. Smith has suggested to me that this Rocky Stream Bush 

 represents a migratory type in contrast to the Coast, Midland and 

 Yellow Wood bushes, which represent the formation on stable topo- 

 graphy. 



