PLANT STEMS 



189 



same observations and experiments on the stem of a small seedling 

 palm tree. 



Experiment 96. Examine a piece of the growing young stem of a 

 willow, apple tree or other woody stem that shows several leaf scars. 

 Is the arrangement of the 

 leaves the same as in the corn 

 stalk? Cut a cross section of 

 this stem and examine it. 

 Does it resemble the cross 

 section of the corn stalk? 

 Strip off a piece of the bark 

 and compare it with the rind 

 of the corn stalk. Examine 

 carefully the smooth, slippery 

 surface of the wood just be- 

 neath the bark. This is the 

 cambium layer. 



Examine the firm wood 

 beneath this layer. Where 

 is the pith in this stem ? 

 With a lens you may be able 

 to see lines radiating from 

 the pith to the circumference 

 of the stern. These are called 

 the pith rays. Cut a length- 

 wise section of the stem and 

 examine it. Are there any 

 fiber-like bundles as in the 



A PINE TREE. 

 Notice the erect position of the stem. 



corn stalk? Cut oif a piece of the stem already examined having the 

 bark on it, or a piece of sunflower stem, and place the end of it in 

 colored water. Allow it to remain for some time and then cut a cross 

 section above the point where it was in the water. Has the water risen 

 and colored this cross section as it did the cross section of the corn stalk ? 



Stems vary greatly in the positions they assume. Some 

 rise firmly erect from the root, like the oak and the pine ; 

 some cling to supports, like the grape and the ivy ; some 

 twine around supports, like the bean ; some creep upon 

 the ground, like the strawberry ; some grow in the form 



