THE PLANT ECOLOGY OF THI-: COAST BELT OF NATAL. 411 



it is preferred, the question may be applied to the vernal 

 species. " Do they tend to increase where the grass is 

 regularly burnt ? " The mere time of flowering, as already 

 explained, is no safe guide, and the collectors' notes on 

 species, as a rule, do not help at all. 



5. EuDERAL Vegetation. 

 (Weeds, etc. The initial stages of subseres.) 



Along roadsides and Kafir pathways, in ditches and 

 quarries, on rubbish heaps and waste land or in cultivated 

 fields, there are found a great many ruderal species which 

 are classified from the standpoint of plant succession as the 

 initial stages of subseres. The original vegetation has been 

 destroyed and the soil is disturbed, but as soon as it is left 

 alone, the processes of repair are initiated and the succession 

 piogresses back to the original grassveld, scrub or forest. 

 The majority of the ruderal species flower profusely and for 

 a long period each year and form large quantities of seed. 

 Many are annuals (therophytes), especially in cultivated 

 land. These gradually give way to perennials as the 

 succession advances. Many of the perennials have a creep- 

 ing habit of growth, which renders them very effective 

 colonisers, and also enables them to withstand adverse 

 conditions. Very few of them can withstand shade, and it 

 is their light requirements chiefly which cause them to give 

 way to other species when the habitat ceases to be interfered 

 with. 



Most of the ruderals of the coast belt are markedly tropical 

 in their affinities, and many species (e.g. of Amarantacete, 

 Euphorbiaceae, etc.), which are widely distributed over the 

 tropics, are included. There are, however, also a number of 

 temperate species, mostly introduced. 



The family AmarantacefB includes a number of species, 

 all of them very abundant: (xomphrena globosa and 

 Alternanthera achyranthoides are both very common 

 along roadsides and garden pathways, etc., the former also 

 proving a troublesome weed in lawns. Other common species 



