388 J. w. BEws. 



and shrubs and innumerable climbers there are two or three 

 hundred tropical species. Only a few of the main families 

 need be mentioned, e.g. Anonaceee, Menispermaceis, 

 Capparidete, Bixineas, Malvacea3, Sapindaceas, 

 Celastrinete, Leguminosas, Combretacea^, Cucur- 

 bitacefe, Rubiacete, Sapotacete, Apocynace^, Con- 

 volvulace^, Yerbenacege, Euphorbiaceae, Urticaceaj, 

 Palm^. The herbs and undershrubs are also largely 

 tropical, the Acanthaceee, Labiatae, Commelinacete, 

 Amarantacete, Euphorbiacea?, Leguminosae and 

 Compositge being well-represented. Among the grasses 

 the numerous tropical or endemic species of Panicum, 

 which are very common around the margin of the scrub, 

 contrast sharply with the earlier grassveld species. 



For farther information the list of species desci'ibed under 

 coast scrub should be consulted and attention given to the 

 relative frequency of each species. A careful study of all 

 the facts, only the barest outline of which has been given 

 above, has led to the conclusion that the following may 

 probably be added to the "Laws of Succession" as formulated 

 by Clements.^ 



In a subtropical region, as the succession 

 advances, the vegetation becomes more and more 

 tropical. 



At present it is perhaps better to regard this as an 

 hypothesis which should be more fully tested in other sub- 

 tropical regions. 



Another general tendency is that widely distributed species 

 usually act as pioneers, or are found in an early stage of the 

 succession. There are, however, exceptions to this, especially 

 in the case of species which are controlled more by edaphic 

 than climatic conditions. Nevertheless, it is particularly 

 true with regard to the majority of the species which have 

 a wide distribution over South Africa. Light-demanding, 

 xerophytic pioneers are able to spread over the drier regions 



' Clements, F. E., ' Research Methods in Ecology,' Lincoln 

 (Nebraska), 1905. 



