STEM VS. ROOT 



17 



each, with waterproof ink mark spaces exactly one-quarter 

 inch apart. Keep the plantlets moist for a day or two, and 

 it will be found that on the stem some or all of the marks 

 are more than one-quarter inch apart; on the root the 

 marks have not separated. The root has grown 

 beyond the last apical mark. (Figs. 25, 26.) 



REVIEW. 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? W T hat 

 is the crown? What becomes of the tops of stemless 

 plants? What are erect, trailing, decumbent, ascending, 

 climbing stems? What are excurrent trunks? Deli- 

 quescent? What is a simple stem? What are strict 

 stems? What are subterranean stems? How are stems 

 distinguished from 

 roots? What is the dif- 

 ference in mode of 

 growth between stems 

 and roots? 



NOTE. The pupil 

 should make marks 

 with waterproof 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 evi- 

 dent on the youngest 

 shoots. 



The pupil should observe the fact that a stem of a plant has wonder- 

 ful strength. Compare the proportionate height, diameter and weight 

 of a grass stem with those of the slenderest tower or steeple. Which 

 has the greater strength? Which the greater height? Which will with- 

 stand the most wind? Note that the grass stem will regain its position 

 even if its top is bent to the ground. Split a cornstalk and observe how 

 the joints are tied together and braced with fibers. Note how plants 

 are weighted down after a heavy rain. 

 B 



25. The marking of 

 the stem and root. 



26. The result. 



