SEASONAL DIMORPHISM OF CHAMAEPHYTES 221 



transpiration rate of desert and Mediterranean plants may also partially be 

 accounted for by the high degree of succulence of the former. 



A comparison between Tables i and 3 shows that the relative decrease 

 in the transpiration rate during summer and the decrease in the transpiring 

 body, are of the same order of magnitude, the two processes playing a 

 more or less equal role in regulating the water output by the plant. When 

 the relative reduction in the total water output is computed, the values 

 obtained range between 90 and 98%. These high values probably account 

 for the fact that chamaephytes play an important role in arid vegetation. 

 As partial drought-evading plants they are intermediate between the 

 drought-evading therophytes, cryptophytes and hemicryptophytes on the 

 one hand, and the drought resisting phanerophytes on the other. Among 

 the perennial plants persisting throughout the year they are distinguished 

 by combining the powers to reduce their transpiring body and their 

 transpiration rate. In this respect they differ from the phanerophytes, 

 whether deciduous or evergreen, except perhaps a few plants hke Anagyris 

 foetida L. and Lycinm spp. 



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