PLANT ROOTS 



367 



which are particularly 

 adapted for doing these 

 different kinds of work. 



Plant Roots. Plant 

 roots usually secure the 

 plant to the ground so 

 that the stem may be 

 supported. They also 

 take up food from the 

 soil and pass it on to 

 the rest of the plant. 

 In most plants all the 

 foods except carbon and 

 a part of the needed 

 oxygen are taken in by 

 the roots. The soil ele- 

 ments that the plants 

 must have are nitrogen, 

 potassium, calcium, mag- 

 nesium, phosphorus, sul- 

 phur, and iron. Water 

 supplies hydrogen and 

 oxygen ; while carbon, 

 another necessary ele- 

 ment, is taken from 

 carbon dioxide of the 

 air. The soil elements 



must be in soluble chemical combinations, such as nitrates, 

 phosphates, sulphates, and so on. 



Experiment 108. Fill three 2-quart fruit jars each about half 

 full of distilled water. Add to the water in the first of these 



THE GRIZZLY GIANT 



The monarch of all plants, 93 feet around 

 the base. Notice the cavalry at the foot. 



