624 
Transactions of the Royal Society of South Africa. 
Ill Natal we have practically no siiow^ — on the coast Ijelt not even frost. 
The frosts are nowhere very severe, the soil rarely being frozen. The 
winters in Natal are, however, very dry, and there are occasional hot winds, 
which add greatly to the dessicating effect. Phanerophytes are confined 
to the sheltered places, where the rainfall and mists are greatest — the 
southern and south-eastern slopes of the hills and edges of the terrace 
plateaux — except in the case of the trees and shrubs of the Thorn Yeld — a 
very xerophytic type. The dryness of the winters, therefore, combined with 
the hot winds, deprive Natal of a Phaiierophytic climate. 
The aljseiice of severe frosts and the dry winters again make the climate 
of Natal not a Hemicryptopliytic one. The high percentage of Chamaephytes 
may, therefore, l)e put down as Ijeiiig caused by the dryness of the winters, 
combined with the absence of severe frosts and intensified by occasional hot 
winds. Natal can then l)e compared with places like Aden and the Libyan 
Desert. We shall find, however, that there are important respects in which 
Natal differs from those places. The percentage of Chamaephytes is about 
the same, but the percentage of Therophytes (Annuals) is very much less 
for Natal — in fact, it is abnormally low. This point will be discussed more 
fully later on, but it is mentioned iiov/ Ijecause one feels constrained to pause 
and ask v.diether the above explanation of the high percentage of Chamae- 
phytes is the only one, and sufficient in the case of Natal. 
The Chamaephytic growth-form, reduced as it is to within 25 cm. of the 
ground during winter, is well adapted to withstanding drought. The shoot 
apices are often protected l)y the older parts, which have died away, and so 
have formed a certain amount of debris. Phanerophytes, as we have seen, 
tend to l)ecome reduced to Chamaephytes l)y the adverse environmental 
factors. But among Chamaephytes we have included sixteen species of 
Streptocarpus, and many soft-stemmed her])aceous plants. These are not 
adapted to withstanding our adverse winter conditions. They do so succes-s- 
fully, because a moist, protected habitat is supplied to them by the 
Phanerophytes that compose the ])ush. 
Take away the Phanerophytes, and the l3ulk of those species of 
Chamaephytes would disappear also. Stress ought to l)e laid on this fact, 
for to a certain extent it contradicts the view that an increase in the number 
of Chamaephytes indicates the influence of drought in Avarm countries. Even 
some of the more xerophytic Chamaephytes are found usually below the 
thorn trees of the Thorn Yeld. Such facts illustrate once more the complexity 
of the whole prol)lem, especially with regard to the influence of one type of 
growth-form on the others. 
HEMICRYPTOPHYTES. 
The aerial portions here are wholly herbaceous and die away at the 
