2— THE ORIGIN OF THE FLORA OF SOUTH AFRICA. 



(A Sketch.) 



By Professor S. Schonland, Ph.D., M.A. 



The question of the origin of the angiospermous Flora of 

 South Africa has been dealt with by many authors, ever since Dr. 

 (now Sir) Joseph Hooker referred to it in the year 1859, in his well- 

 known " Introduction to the Flora of Australia." As a rule, it 

 has been treated as a side-issue, and, moreover, the authors who con- 

 cerned themselves about it were as a rule largely influenced by what 

 IS known of the development of the Floras of the Northern Hemi- 

 sphere. In his " Entwicklungsgeschichte der Pflanzenwelt seit der 

 Tertiarzeit," (Leipzig 1879, 1882), Professor Engler has dealt with 

 it in the most cautious and reserved manner, and even quite recently 

 he has expressed himself to the effect that the relations of the Flora 

 of South Africa to the Flora of Australia, are a great enigma, rela- 

 tions which have to be explained, if one wants to get a true under- 

 standing of the origin of our Flora. The difficulties of dealing with 

 this subject satisfactorily are very great, and the data for a final 

 solution are absent at the present time, and may be for ever hidden 

 from us. However, there are a good many facts known which make 

 it at all events probable that the development of our Flora has taken 

 place along certain lines, which I propose to bring before you to-day. 

 It is impossible in a short paper to deal exhaustively with the evi- 

 dence on which my conclusions are based, but I hope to be able to 

 publish this evidence at no distant date. Any theory accounting for 

 the origin of the South African angiospermous Flora must take 

 cognizance of the fact that no traces of a glacial period have been 

 discovered in South Africa later than Permian times. I am aware 

 of the fact that Passarge thought to have discovered proofs of the 

 former existence of pluvial periods in the Kalahari, corresponding 

 to the glacial periods in the Northern Hemisphere, but I think that 

 his evidence must be looked upon with suspicion, and that while it 

 is certain that rainy periods have occurred, even in the Kalahari, they 

 can in no way be correlated with the glacial periods of the Northern 

 Hemisphere, and that, broadly speaking, the climate of South 

 Africa has, within certain limits, been constant at least since early 

 Cretacous times. This view, which I came to from consideration of 

 purely local facts, is also held by Professor J. W. Gregory, and it is 

 important that it should be confirmed by such a high 

 geological authority, because this view implies that the 

 glacial periods in the Northern Hemisphere have been due 

 to local causes, and not to extra-terrestrial causes such 

 as e.g., a change in the inclination of the ecliptic of the earth. We 

 mav also state that there are no facts known which would lead us to 

 the conclusion that there has been a considerable Southern extension 

 of the African Continent since early geological periods, at all events 

 not since Cretaceous times, and we may therefore come to the con- 

 clusion that the ancestors of a good many types of plants now found 



