CHAPTER VI 

 STEMS 



62. What the Stem is — The work of taking in the raw 

 materials which the plant makes into its own food is done 

 mainly by the roots and the leaves. These raw materials 

 are taken from earth, from water, and from the air (see 

 Clhapter XIII). The stem is that part or organ of the plant 

 which serves to bring roots and leaves into communica- 

 tion with each other. In most flowering plants the stem 

 also serves the important purpose of lifting the leaves 

 up into the sunlight where alone they can best do their 

 special work. 



The student has already, in Chapter III, learned some- 

 thing of the development of the stem and the seedling; 

 he has now to study the external appearance and internal 

 structure of the mature stem. Much in regard to this 

 form and structure can conveniently be learned from the 

 examination of twigs and branches of our common forest 

 trees in their winter condition. 



63. The Horse-Chestnut Twig.^ — Procure a twig of horse-chestnut 

 eighteen inches or more in length. Make a careful sketch of it, 

 trying to bring out the following points. 



(1) The general character of the bark. 



1 Where the buckeye is more readily ohtained it will do very -well. Hickory 

 twigs answer the same purpose, and the latter is a more typical form, having 

 alternate buds. The magnolia or the tulip tree will do. The student should 

 (sooner or later) examine at least one opposite- and one alternate-leaved twig. 



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