8 Bews , — Some General Principles of Plant Distribution as 
aerated loams, or sometimes sandy, poor in plant food. Vegetation grass- 
veld, scrub, and forest. 
7. Coast-belt of the Eastern side . Summer rainfall 30 to 40 inches. 
Temperatures uniformly fairly high, but not extreme. Frosts absent. 
Soils varied. Vegetation grass-veld, scrub, and subtropical forest. Flora 
with close tropical affinities (see Bews, 12 ). 
Widespread Species. 
Species which belong to the climax plant communities in the western, 
south-western, and central regions often are found to belong also to early 
stages of the plant succession on the eastern side, so that the arranging of 
the climatic areas in an ascending series reproduces, to a certain extent, the 
various stages of plant succession in the higher types. Any species which, 
under favourable conditions, is able to oust another species is to be reckoned 
of a higher ecological type. The primitive ecological species tend to be 
widespread, the higher types more restricted in their ranges. For instance, 
if we consider the 320 species which are common to the Cape Peninsula 
and Natal, we find that, while they belong to widely different growth-forms 
and show no possible phylogenetic relationships, they practically all agree in 
belonging to early stages of the succession as ruderals in subseres or marsh 
and aquatic plants in the hydrosere, as litoral plants, or as xerophytic light- 
demanding species in the xerosere ( 13 ). 
A little consideration will show why, in a country like S. Africa, wide- 
spread species usually belong to early stages of the succession. We have 
seen that South Africa shows a number of distinct climatic areas with 
increasing mesophytism in a general way from west to east, but with 
a south-western area, which, though it has a fairly high rainfall, receives 
that rainfall in winter instead of summer and is separated from the regions 
of summer rainfall by the dry Karroo. Nevertheless, traversing all the 
areas there are found primitive habitats, which are to a large extent uniform. 
They are : . 
1. Cultivated land, waste places, &c.,°with ruderal species. 
2. Lakes, streams, marshes, with aquatic or semi-aquatic species. 
3. The seashore habitat, mostly sandy, with widespread littoral or sand- 
dune plants. 
4. To a less extent the mountain ranges which cross South Africa. 
5. Drier areas in the (thorn-veld) river valleys, open rocky situations 
on steep slopes, &c., are common all over the eastern side and differ but 
little from the Karroo and western areas as a whole. ' They are occupied 
by primitive ecological types which are soon ousted by others in the 
east. 
In addition to these primitive habitats, it should be remembered that 
South Africa lies south of a fairly uniform tropical region to the north, 
