7' 



PRESIDENTIAL ADDRESS SECTION C. 



— (a) those crops known to be unsuited to the country, with 

 notes as to the reasons on which that conchision is based; {h) 

 crops not yet grown commercially, but considered worth trial, 

 with notes on the localities considered most likely to suit their 

 requirements. 



Improvement by Breeding. 



In connection with this branch, an important subject for 

 report would be the ix)ssibilities of improvement by breedin;:; 

 of our wild plants of economic value. To this should be added 

 a report on what has been done in other countries in the way 

 of improving cultivated crops, and the bearing this may ha\e 

 on our own development. 



The Ecological Survey. 



Another and very important line of surve}' work already 

 alluded to is that of the ecological distribution of our plants ; 

 that is to say, their relation to soil, temperature, rainfall, alti- 

 tude, and other factors which affect their distribution. 



From the j^urely scientific point of view we want to know 

 precisely why, for instance, we find forests hanging to certain 

 parts of the eastern slope of the Drakensberg, and not to other 

 parts ; why the upper levels of the great central plateau are so 

 generally treeless, while the higher kopjes and hills often produce 

 trees and shrubs, and the bushveld, 1.500 t(i 2.000 feet lower, is 

 well covered with trees? Why do some ])1ants grow only on 

 saline ("brak") soils, some on limestone soils, and some on 

 sands, while others prefer clays? 



We find .'^ome plants growing in the shallowest soil, overlying 

 rock, where they sometimes get practically no rain for four and 

 even five months, and if given excessive moisture, they die; 

 others, again, only grow where there is a constant and large 

 supply of moisture, and some will (^nly Hvl- in ])ermanent water. 

 On the other hand, we find .some species of aquatic plants 

 growing in ephemeral |X)ols and " pans," and remaining dormant 

 for five to seven months while the pools are dry; others, again, 

 remain dormant while their roots are submerged for five t(_> 

 seven months, and produce foliage and flowers only when X\\" 

 mud is ex])osed and drying off. 



While the desire for knowledge urges us to study the causes 

 of facts, of which these are a few taken at random, the reasons 

 governing them may have an important bearing on agricultural 

 problems. The conditions under which a plant grows naturally, 

 suggest methods of treatment to be applied to it and to j)lants 

 of a like nature under cultivation. I do not mean to infer, 

 however, that plants should not be cultivated under conditions 

 different from those under which they grow in a wild state ; we 

 have many examples to prove the contrary. But the suggestions 

 taken from nature, if properly interpreted, should be of assis- 

 tance to the cultivator. 



Ecology can be of great use in another wav, especially in 

 a new country. Carefully studied and correctly interpreted, the 



