78 



Principles of Plant Culture. 



Section VII. The Stem 



114. As the root develops from the base of the 

 hypocotyl, the plumule, or primary shoot (56), develops 

 from the other end and becomes, at least for a time, the 

 main axis or stem of the plant. 



115. The Stem is, 

 generally speaking, 

 the part of the plant 

 that supports the 

 leaves. In excep- 

 tional cases, as in 

 the potato (Fig. 34) 

 and quack grass, a 

 part of the stem 



u.si 



grows beneath the 

 ground, on which 

 the leaves usually 

 do not develop {un- 

 derground stems); 

 and in a few plants, 

 as in some cacti, the 

 stem performs the 

 whole office o f 

 leaves. The stem 

 may be strong 

 enough to support 

 its own weight, as in trees and shrubs, or it may depend 

 upon other objects for its support, as in vines. 



116. Nodes and Internodes. Unlike the root, the stem 

 is developed in successive sections, comparable in part 

 to the stories of a building. Each section or story 



Fig. 34. Potato plant. U. St., under- 

 ground stems; B, roots. The tubers are the 

 thickened distal* ends of the underground 

 stems. Much reduced. (After Frank and 

 Tschirch.) 



* See foot note on page 79. 



