CHAPTEE XIV 



MBSOPHYTE ASSOCIATIONS 



145. General characters. — Mesophytes make up the com- 

 mon vegetation of temperate regions, the vegetation most 

 commonly met and studied. The conditions of moisture 

 are medium, precipitation is in general evenly distributed, 

 and the soil is rich in humus. The conditions are not ex- 

 treme, and therefore special adaptations, such as are neces- 

 sary for xerophyte or hydrophyte conditions, do not appear. 

 This may he regarded as the normal plant condition. It 

 is certainly the arable condition, and most adapted to the 

 plants which men seek to cultivate. When for purposes 

 of cultivation xerophyte areas are irrigated, or hydrophyte 

 areas are drained, it is simply to bring them into mesophyte 

 conditions. 



In looking over a mesophyte area and contrasting it 

 with a xerophyte area, one of the first things evident is that 

 the former is far richer in leaf forms. It is in tire meso- 

 phyte conditions that foliage leaves show their remarkable 

 diversity. In hydrophyte and xerophyte areas they are apt 

 to be more or less monotonous in form. Another contrast 

 is found in the dense growth over mesophyte areas, much 

 more so than in xerophyte regions, and even more dense 

 than in hydrophyte areas. 



Among the mesophyte associations must be included not 



merely the natural ones, but those new associations which 



have been formed under the influence of man, and which do 



not appear among xerophyte and hydrophyte associations. 



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