"13° 



ROOTS 



(2) That part of the root in which cell enlargement 

 principally occurs lies directly behind the apical meristem ; 



that is, directly be- 

 - "I -1 J hind the meristem 

 mi which is at the apex 

 or tip of the root. 

 This part is called 

 the region of elonga- 

 tion. In this region 

 the cells grow in 

 length more than they 

 do in width. 



In stems also the 

 region of elongation 

 lies directly behind 

 the growing tip. It 

 is usually several 

 inches long ; often 

 more than a foot 

 long. In roots, how- 

 ever, this region is 

 much shorter than in 

 stems. It is hardly 

 ever more than two 

 fifths of an inch long, 

 and often not more 

 than half of that. 

 Evidently root cells 

 finish their growth in 

 length more quickly than stem cells do ; they mature more 

 quickly than stem cells. 



It is simple to show by experiment what part of the root 



Fig. 42. — A lengthwise section of a root tip. The 

 part marked c is the root-cap. Just above 

 this is the meristem, the region of cell division. 



