630 Transactions of the Uoyal Society of South Africa. 
It has been pointed out by the writer elsewhere (1, 2) that when culti- 
vated land is allowed to revert to veld, the annual species are gradually 
replaced by perennials. 
The total number of Therophytes is cir. 197, including thirty-six species 
of grasses. Several species here classed as annuals also occur as perennials 
while certain species classed as perennials always flower the first year and 
may be annuals. 
Since the majority of the annuals which do occur in Natal are, as already 
mentioned, the weeds of cultivated land, and a high proportion of them 
are exotic, the climate of Natal is obviously not a Therophytic one. Though 
the drought is severe in winter, there is plenty of rain in summer. 
The comparative scarcity of Therophytes must therefore be put down to 
two causes : 
(1) The fact that Natal is not a country under high cultivation. 
The small area under mealies, etc., is out of all proportion to the vast 
stretches of virgin veld. It is true that a good deal of land is now being 
planted with Wattle {Acacia mollisslma), but in the Wattle plantations 
weeds and all kinds of undergrowth are very scarce. 
(2) The fact that Natal is a region of summer rainfall. On the west and 
south-west side of South Africa the rainfall is in winter, and the summers are 
dry. Annuals are undoubtedly more abundant there. An analysis of the 
flora of South Africa, as a whole, would show a higher percentage of annuals. 
Though the writer is not in a position to put forward such an analysis, there 
are plenty of facts to support this statement. For instance, 27 species of 
Senecio were included in the class " Annul " by Harvey in vol. iii of the 
Flora Capensis. That was published in 1864, and now the list might 
be extended. 
In Natal, though Senecio is one of our largest genera {cir. 80 species 
and varieties) only one or two are annuals, and not one of Harvey's original 
27 is recorded for Natal. Again, Phyllopodimn has 18 South African species, 
of which 12 are annuals. Only one of the 12 belongs to Natal. Examples 
might be multiplied. 
The hot, dry summers of the western portion of South Africa give a 
Therophytic climate which contrasts strongly with the eastern side. 
The classes of growth-forms described so far form a fairly definite series 
from Phanerophytes to Therophytes, showing increased protection for the 
renewal buds during the adverse season. There are certain smaller classes 
of growth-forms which do not come into the series. Of these, Eaunkiaer 
included two — the Stem Succulents and Epiphytes. A third is here added — 
the Heterophytes. 
