176 SCIENCE IN AFRICA 



Diseases caused by rust fungi are important. Those which affect 

 grain have been studied specially in South Africa by Dr. Pole 

 Evans, and in Kenya, where McDonald's work is noteworthy. 

 Some success has already resulted from attempts to breed strains 

 of wheat resistant to these diseases. The coffee rust fungus, 

 Hemileia, is under investigation at Amani. For all these studies 

 the Imperial Institute of Mycology at Kew is now the centralizing 

 headquarters for information and research. 



PRESERVATION OF FLORA 



The preservation of the indigenous flora is an aspect of botany 

 which perhaps deserves more attention than it has received in 

 connection with the development of national parks and nature 

 reserves. The vegetation of Africa is changing very rapidly, not so 

 much in the sparsely populated inland plains, where vast areas are 

 still unaffected, but in the more densely populated regions, which 

 are subject to influences such as shifting cultivation,^ the introduc- 

 tion and spread of exotic food-plants, and afforestation with exotic 

 trees. Even the introduction of foreign plants into gardens may 

 have unexpected results. This is the case particularly with fast- 

 growing trees such as wattles and gums which multiply very 

 rapidly under favourable circumstances, and dispossess the indi- 

 genous trees and shrubs. 



It is necessary also to consider the provision of reserves for the 

 indigenous flora in addition to forest reserves. Such areas need 

 not be very large, but if they are to have their full educational 

 value they should be situated in accessible places. Under suitable 

 management they could with advantage be made to serve the 

 purpose of botanical gardens. A resolution urging the maintenance 

 of representative areas of forest in their primeval condition was 

 passed at the Empire Forestry Conference in South Africa in 1935. 

 In parts of South Africa, action has already been taken: nature 

 reserves have been established by the Department of Agriculture 

 and Forestry where no planting of trees, no grazing, and no des- 

 truction by fire will occur. Some of these are areas of macchia- 

 like vegetation, notable for their beautiful plants, and others are 



^ See Chapter vii, p. 187 and Chapter xiii, p. 376. 



