STRENGTH OF ROOTS 



ground life is often visible on the surface. Roots, and 

 particularly tree-roots, are often extraordinarily strong. 

 Kerner, in his invaluable Natural History of Plants^ has a 

 beautiful picture of a young larch tree which had grown in 

 a fissure of a huge boulder. 



In attempting to grow, the root had forced up part of this 

 stone. It was estimated that it had lifted a weight of 

 3000 lb., though it was only some ten inches in diameter. 



Along a dry-stone wall, or even near houses, the growth of 

 tree-roots very often damages the entire wall, which may be 

 entirely overthrown if the tree is too near. The force of the 

 growth of the roots is so great that even a six-foot stone 

 wall cannot keep them down. 



Quite a young seedling root, in forcing itself through the 

 soil, may exercise a pressure of two-thirds to four-fifths of a 

 pound ! 



This is of course necessary, if one remembers that it has 

 to drive itself through the earth, pushing aside and com- 

 pressing the earth particles along its course. 



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