CHAPTER II 

 ROOTS 



WE ALL know that plants have roots, but they are usually 

 buried in the ground and thus hidden from sight and are not 

 especially attractive. Therefore, most persons prefer to study 

 the more prominent and pleasing parts of the plant. How- 

 ever, no part is of greater importance to the plant as a whole 

 than the root system. When the seed sprouts, the root is the 

 first organ of the embryo to break through the seed coats. (Figs. 

 2 d, 4, 6 and 7 a.) It grows downward, away from the light, 

 but into the soil which contains the food and water. This ten- 

 dency to go downward is called geotropism. 



The soil should contain the necessary supply of food and 

 moisture, and should be of such character that the roots can 

 penetrate it readily if the plant is to make its normal growth. 

 But we shall learn later that all plants do not require the same 

 amounts of moisture, nor the same amounts and kinds of food. 

 The farmer cultivates the soil for his crop plants and thus aids 

 the plants in the work necessary for their growth. 



Extent of Roots. The root usually grows very rapidly, and 

 when the entire root system is compared with the parts of the 

 plant above ground, it is found to be much more extensive than 

 we have ever imagined. When we pull a plant from the soil 

 a very large number of the roots are broken off and left be- 

 hind. Therefore, we get a very imperfect idea of the root 

 system and its ramifications in the soil. But if a plant is grown 

 in a pot of loose soil, and this soil carefully washed from the 

 roots we begin to have some slight idea of the very great value 

 of this part of the growing plant. It has numerous branches, 

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