CHAPTER VII. 



STRUCTURE OF STEMS AND THE WATER PATH IN 



STEMS. 



89. In the study of seeds and their germination (Chapters 

 I and II) it was found that certain seedlings, the corn, for example, 

 has one cotyledon, while the pea, bean, etc., 



have two cotyledons, or seed leaves. Plants 

 belonging to the first class are called Mono- 

 cotyledons, while those belonging to the second 

 class are called Dicotyledons. The fact that 

 most plants of the first class have one coty- 

 ledon, and those of the second have two 

 cotyledons, led to the adoption of these names. 

 There are, however, other important distinc- 

 tions. The anatomy or structure of the plants 

 belonging to these two classes show certain 

 points of agreement. Most of the members 

 of the monocotyledons possess one type of 

 structure, while the members of the dicotyle- 

 dons possess another type of structure. 



STRUCTURE OF THE STEMS OF 

 MONOCOTYLEDONS. 



90. The corn plant, the cereals like wheat, 

 the grasses, etc., are good examples of mono- 

 cotyledons; the stem is distinctly marked off com plant, a mono- 

 into nodes, or joints, and internodes. The 



leaf is attached at a node. The three parts in a typical leaf, as in 

 the corn, are as follows: The sheath surrounds the stem, the blade 

 is the free part of the leaf, the ligule is a slight membranous 



