292 LESSONS IN AGRICULTURE 



Man has made the stems of plants serve him in other 

 ways. They provide him with lumber, posts, poles, and 

 fuel. They serve in ma"ny cases as food, and indirectly 

 furnish materials both for food and clothing. 



Stem structure. Unlike the root, the stem is devel- 

 oped in sections, similar in a way to the stories of a 

 building. Each section or story consists of one or more 

 leaves attached to the farthest end of the section. The 

 part of the stem to which the leaves are attached is called 

 the node, and the part between the leaves is called the 

 internode. The nodes are the points where the lateral 

 buds are formed, and the internodes elongate causing 

 the growth in length of the stem. The structure of the 

 inside of stems will be seen in the practical exercises 

 to follow. 



Habits of growth. Plants have stems that; are 

 erect, standing above ground, and strong enough to sup- 

 port all the leaves and branches. The stems of other 

 plants are twining, or lie prostrate upon the ground. 

 The stems of some plants are entirely underground, 

 either condensed into short bulbs or running like root- 

 stocks for a considerable length, bearing leaves above 

 ground from their nodes. Still other plants are with- 

 out stems, bearing their leaves from the root crowns. 



Practical Exercises 

 1. Types of Stem Structure 



Each pupil should have sections about six inches long, 

 of corn-stalk and of a twig from a tree. 



Compare the cross sections of the two stems. Note 



