18 



THE STEM 



Eeview. — What is the stem 

 system ? What does the stem do ? 

 How long may the stem persist ? 

 What is meant by the habit of a 

 plant? Name some kinds of habit. 

 What are so-called stemless plants? 

 What is the crown ? What becomes 

 of the tops of stemless plants ? 

 What are erect, trailing, decum- 

 bent, ascending, climbing stems? 

 What are exeurrent trunks? Deli- 

 quescent? What is a simple stem? 

 What are strict stems ? What 

 are subterranean 

 stems ? How are " 



What is the differ- 



stems aistinguished from roots? 



ence in mode of growth between stems and roots? 



Note. — The pupil should make marks with water- 

 proof ink (as Higgins' ink or indelible marking ink) 

 on any soft growing stems — as geranium, fuchsia, 

 grass, the twigs of trees. Note that the separation of 

 the marks is most evident on the youngest shoots. 



The pupil should observe the fact that a stem of 

 a plant has wonderful strength. Compare tlie pro- 

 portionate height, diameter and weight of a grass stem 

 with those of the slen- 

 derest tower or steeple. 

 Which has the greater 

 strength ? Which the 

 greater height ? Which 

 will withstand the most 

 wind ? Note that the 

 grass stem will regain its 

 position even if its top 

 is bent to the ground. 

 Split a corn stalk and 

 observe how the joints 

 are tied together and 

 braced with fibers. Note 

 how plants are weight- 



ed down after a heavy -''■ ^^^T "J^''^'^^, 



'' of the stem and 



rain- root. 



26. The result. 



