THE POWER OF GROWTH IN PLANTS 



231 



THE POWER OF GROWTH IX PLAXTS 



Bt GEORGE E. STONE 



BOTANIST, MASSACHUSETTS AGKICULTURAL COLLEGE 



IT has been a matter of more or less common observation from time 

 immemorial that plants possess the power to overcome obstacles. 

 Some species of trees are not particular where they grow if there is 

 enough soil and moisture, their roots often seeking places where appar- 

 ently insurmountable obstacles must be overcome. In spite of the doubt 

 often expressed, there are on record many cases of trees lifting large 

 weights; and in mountainous regions large boulders are often found 

 displaced by roots growing among them. Some trees even lift them- 

 selves slightly from their original positions into the air, as is evident 

 from the location of the root buttresses, which are often found exposed 

 above the surface, sometimes for a considerable distance. An instance 

 is known of a tree growing in the center of a millstone, which later 

 completely filled the hole and actually raised the stone from the ground. 

 Brick and concrete sidewalks are often ruptured and curbings dis- 

 placed by roots, due to their growth in diameter, and perhaps in some 

 cases to the actual uplift of the tree trunk and roots. The writer has 

 had under observation for many years a black birch (Betula lenta L.), 

 one root of which has entered a fissure in a large boulder and is slowly 

 but constantly lifting this enormous weight. The fissure is at an 





























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Fig. 1. Showing large black birch (Betula lenta L. ), one of whose roots 

 is lifting an 18-ton boulder. 



