Plant Succession and Plant Distribution in 
South Africa. 
BY 
J. W. BEWS, M.A., D.Sc., 
Professor of Botany in the Natal University College. 
Introduction. 
NY study of plant distribution in any country must take into account 
Uf\ the interesting hypothesis of age and area, which has been fully 
illustrated by Dr. J. C. Willis in numerous recent papers (14-21). When 
his first papers on Ceylon appeared, I was engaged on a fairly detailed 
analysis of the extensive grassland flora and plant succession in South 
Africa (8), and a somewhat superficial application of the age and area 
hypothesis to the South African grasses seemed on the whole to con- 
firm Willis’s results for Ceylon. Endemic species of Gramineae in South 
Africa tend to have comparatively narrow ranges, while non-endemic species 
have usually wider ones. At the same time, even granting these facts, and 
the much more definite ones brought forward by Willis, to be true (as 
of course they undoubtedly are), and granting further the perfectly reason- 
able contention that the longer a species exists in any country the wider will 
be its distribution in that country, yet it appeared clear that in a country 
like South Africa, with its great variations in climatic conditions, the action 
of the age and area rule must be profoundly modified. 
The south-western region in South Africa is distinguished by a winter 
rainfall and dry summers, and has a distinctive flora with a very large 
number of endemic species which range all over it (5). The eastern side 
of the sub-continent has summer rains, and a flora which differs very greatly 
from the south-western. Nevertheless, in the south-western region, even 
in the Cape Peninsula on the western side of it, there are small outliers of 
eastern forest in certain moister climatic situations. The species compos- 
ing such forests are eastern species, and for the south-western region would 
rank as ‘ wides ’, yet they have a small range in the south-western region, 
and would be considered as rare, or rather rare according to Willis’s scheme. 
In the same way numerous south-western species extend eastward along 
[Annals of Botany, Vol. XXXI V. No. CXXXIV. April, 1920.3 
