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ECOLOGICAL RELATIONS 



The Mesophyte societies are those made up of plants which 

 require a fair amouut of rainfall. The forest and prairie 

 plants and most of our agricultural plants are mesophytes. 



The Xerophyte societies require very little water and in- 

 clude the desert plants. 



Fig. 84. — Zone formation of vegetation dependent upon depth of water. 



In addition to these societies we have also 



The Halophytes or those plants which grow in salt water 

 and salt marshes, and 



The Tropophytes which are mesophytic in habit for a part 

 of the year and xerophytic in habit for the remainder. 



Soil. — The majority of plants with which we are familiar 

 grow in the soil, but we must not forget that a great number of 



