STRTN I I RE i iF l;< >< >TS 



267 



the phellogen and the corky tissue outside of it. Draw. 

 The relation of bark to woody tissue in pine is shown in 

 Fig. 4lo. Cork tissue may be studied to advantage in 

 the skin of the potato. 



432. structure of roots. At the growing poinl 

 the root has a cap (of small compacl cells) which 

 protects the deli. -ate tissues from injury (Fig. 395). 

 Such a protection is not found in growing points (bui 

 of stems. In their internal structure roots differ from 



UO. White pine Btem in radial longitudinal Bwtion. 

 Tracheids on the left with medullary isslngtbem. Next to t hi 



Mil- phloem, then fundamental tiiMue, then the dart bai 



shms, especially when very young. iToung i< < >i - have 

 the radial type of bundles, and there is tlen usual!} 

 only one bundle iii tie- root, 'lie- number of Btrands 

 of sylem radiating from the center differs with 1 1 < 

 plant. Iii roots also there is almost uniformlj present 

 a true endodermis. This layer i- found just within the 

 cortex ami i> composed of rather thick-walled cells. 1 1 < \\ 

 ever, man} rhizomes and Btems have a true endodermis. 



To Study com r""/s: Prom the fOOt of Indian COril a l'\\ 



week-, old cut iliin cri .'lion-; stain and mount. With 



the ,-iiil of He' 1"\\ power mal ketch Bhowinjj tin 1 



