126 



such a large proportion of the total flora is involved, and 

 undoubtedly there are many interesting problems to be 

 encountered. 



Grass burning has the effect of generally increasing the 

 abundance and extent of vernal aspect societies since their 

 development as pointed out above depends so much ou their 

 being able to make an early start in Spring. If the old grass 

 is burnt off the surface of the soil is heated more easily, the 

 numerous aspect flowering plants obtain the necessary rise 

 in temperature, and they are able to spread considerably 

 before the grass grows tall enough to stop their growth by 

 shading them. This goes on year after year. Vernal aspect 

 societies are relatively rare in veld that has been left unburnt. 



Aestival and Autumnal Aspects. 



It is hardly worth while distinguishing between these in 

 the Eastern grassland of South Africa. The grasses during 

 summer grow taller, and there is always a rise in the level of 

 each succeeding aspect. The numerous vernal aspect societies 

 cease to be so prominent, though of course they have not dis- 

 appeared. As a matter of fact, many of the species mentioned 

 above continue to be found in flower through the summer 

 months, but even if a species flower fairly late, it may belong 

 to the vernal aspect, if it is more conspicuous in the Spring. 

 The great majority of the Veld plants are vernal, for in 

 Autumn the rank growth of grass tends to hide everything. 

 The chief autumnal societies really belong to transitional 

 types, the species being usually shrubby. Only a few wide- 

 spread examples will be mentioned. 



The Bracken fern Pteris aquiliiui is one of the most 

 important. Among the Compositae Artemesia afra (umHlon- 

 yane) and several species of Vernonia, Aster, Nidorella, 

 Athanasia, H elicit ry sum, Berkheya, Senecio are frequent, in 

 fact compared with the others, this great order is even more 

 prominent in the autumn than in the Spring. The Legumin- 

 oseae, on the other hand, are not so prominent in autumn. 

 Few examples of the Asclepiadaceae, so abundant in Spring, 

 can be found in autumn. The bulbous Monocotyledons, too, 

 are much reduced, though a few, e.g., Watsonia densiflora, 

 form rather extensive societies. The Labiatae include one 

 widespread example, Leonotis leonurus (iMunvane). Apart 

 from the grasses, to the plant collector the Veld in autumn 

 appears a singularly barren field, when he compares it with 

 the almost overwhelming profusion of flowers found there in 

 the Spring. 



