STEMS 



49 



A sweet potato, however, is truly a root, and it does 

 give rise to new plants. The dahlia is another example of 

 a plant whose true roots are used for reproduction. The 

 silver poplar, the osage orange, and some kinds of willows 

 give off new plants which rise as branches from their roots. 

 In general, however, true roots are not much used for di- 

 rect reproduction. Indirectly, of course, they have an im- 

 portant part to play, for without the work of roots 

 no part of the plant could reproduce. 



i6. Stems. — Stems are the great helping organs of the 

 plant. They appear to be more concerned in helping 

 other organs to work than they are in doing a special 

 work of their own. They appear to be chiefly concerned 

 with getting other organs into positions in which these 

 other organs can work to best advantage. Stems deter- 

 mine the positions of the leaves and the flowers. Flowers 

 to accomplish their work successfully require positions 

 of a certain sort just as leaves do. Fruits, as you know, 

 follow the flowers, and for them too, certain positions 

 are much more advantageous than others. The stems 

 serve the fruit in this matter just as they serve the flowers 

 which precede them. 



The stems are the great intermediate organs of the 

 plant. Roots must be in the soil. Leaves must be in 

 the light. -Both must be separated and yet connected. It 

 is the stem which separates them and yet connects them. 

 It furnishes channels through which move the foods and 

 the materials from which foods are made. Often food is 

 stored up in stems to be used later, perhaps next season, 

 before the leaves have begun their work. Underground 

 stems especially are used by the plant in this way. 



