608 Transactio7is of the Eoyal Society of South Africa. 
Eaunkiaer agree more or less in emphasising the importance of the adaptations 
which enable plants to live through the adverse season. Warming's system 
is built on a broader foundation. He takes into account all the main 
adaptations and the main factors of the environment. His system shows a 
marked contrast to that of Raunkiaer, in that the latter chooses one main 
factor and to a large extent neglects the others. 
Any worker who has to select a system will find that he must be guided 
by two principles : 
1. Which system is most natural and scientific and interprets best the 
ecological facts. 
2. Which system, under any given circumstances, can be applied most 
usefully. 
As far as the first principle is concerned, in the writer's opinion, 
Warming's system is preferable to any of the others, though it, too, leaves 
much to be desired. But in attempting to apply it to the vegetation of Natal, 
the writer found that his knowledge of the facts was not sufficient to enable 
him to do so successfully. 
Raunkiaer's system is much easier to use. It has been adopted by other 
Danish botanists, such as Ostenfeld (17) and Paulsen (18). An excellent 
account of it is given by W. Gr. Smith in the Jour7ial of Ecology, vol. i, 
No. 1 (22). Not only is it easier to use, but it has the further advantage of 
lending itself to statistical and therefore comparative methods. The basis 
of the system is the nature and degree of protection possessed by the buds 
or shoot apices during the adverse season— i.e. in the case of Natal during 
the winter dry season. Eaunkiaer has modified his system slightly since 
1903. In a paper published in 1908 he adopts the following ten main 
classes of growth-forms or " life-forms " : 
1. S. = Stem-succulents. 6. Ch. = Chamaephytes. 
2. E. =^ Epiphytes. 7. H. = Hemicryptophytes. 
3. M.M. = Megaphanerophytes and 8. G. = Geophytes. 
Mesophanerophytes. 9. H.H. = Helophytes and 
4. M. = Microphanerophytes. Hydrophytes. 
5. N. = Nanophanerophytes. 10. Th. = Therophytes. 
Phanerophytes are the trees and shrubs having their buds in the air. 
The buds may be naked or scaly, large or small. Phanerophytes may be 
deciduous or evergreen. Megaphanerophytes grow over 30 metres high 
(100 ft.). Mesophanerophytes, 8-30 metres (26-100 ft.). Microphanero- 
phytes, 2-8 metres (6-26 ft.). Nanophanerophytes, less than 2 metres 
(6 ft.). 
Chamaephytes include a variety of forms that have their shoot apices 
on the surface of the ground or not more than 25 centimetres (10 in.) above 
it. This does not mean that the plant during the vegetative season is not 
more than 25 centimetres high. The herbaceous parts may grow tall, but 
