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PLANT GEOGRAPHY 



mesophyte, originally meant to apply to plants but little 

 specialised in structure with reference to moisture, and 

 flourishing in situations neither markedly wet nor 

 markedly dry (of which perhaps, po-ophytes or meadow- 

 plants are, perhaps, the most typical examples), has now 

 been applied to more hygrophilous types, and many 

 plants originally so called are now termed tropophytes. 



FIG. 12. Open reed-swamp association. Scirpus lacustris and 

 Castalia alba. (From photograph by Miss M. Pallis.) 



At the same time, even the sclerophyllous Holly and 

 Spruce have been termed mesophytes. Perhaps our 

 English Oak, Hornbeam, Hazel, and Hornbeam woods 

 on clay or loam may be considered mesophytic ; but all 

 these constituent trees are tropophytes. This term was 

 coined for those plants, including most of those of tem- 

 perate regions, which, with thin deciduous leaves and 

 rapid transpiration at one season, have corky bark and 

 thick bud-scales to resist drought at another. 



Xerophytes are plants adapted to a limited supply of 

 physiologically available water. Most of their familiar 

 structures, deep roots, thick cuticle or cork, enlarged or 



