THE lU.AX STEM 



271 



Figure 264. — Fibrous Roots of 

 Buttercup. 



How do they differ from the bean roots ? 



plied with the used-up ele- 

 ments through the aid of 

 fertilizers and chemicals. 



When water containing 

 minerals in solution is 

 taken in through the root 

 hairs, it is passed along 

 by osmosis to the woody 

 layer of the rootlets and 

 thence to the primary root 

 from which" it is distrib- 

 uted to the parts of the 

 plant above ground. Here 

 it is made into food and 

 carried by the phloem of 

 the vascular bundle to 

 all parts of the plant. 



The root system of a plant, then, serves two main purposes : 

 to hold it fast in the ground, and to absorb water from tin- 

 earth. In passing through the soil this water has taken up 

 mineral substances which will enter into the plant's food. 



LABORATORY STUDY OF ROOTS 



Cut a carrot crosswise and lengthwise, and note the centra] cylinder 

 and cortex. Cut across one of the larger bean roots, noting (1) the cen- 

 tral woody cylinder ; (2) the softer ring surrounding it; (3) the outer 

 epidermis. Cut a root lengthwise and find the same tissues. Examine 

 sprouted barley for root hairs and root caps; also a radish seedling for 

 root hairs. Stand a cut-off root in red ink for a few hours. Make a 

 and lengthwise sections, noting what part has been stained by the ink. 

 This shows the routes through which absorbed water travels. 



208. The Bean Stem. — The bean stem is made up of three 

 parts : (1) a central pith where food is stored ; (2) woody 

 fiber which conducts water; and (3) a bark and an epidermis 

 which cover and protect it. The stem aa a whole holds up 



