THE WORK OF STEMS 101 



Conclusion. — Where do the leaves grow out from the 

 stems of each of the plants? Are the leaves of- the com 

 plant arranged on opposite sides of the stem, or are they 

 arranged spirally? How are they arranged on the morn- 

 ing glory? Of the three kinds of stems, which would 

 need to be most rigid? Why? Do you find it so? 

 Which would need the strongest anchorage roots ? Why ? 

 Name three cultivated plants with erect stems, three with 

 climbing stems and two with prostrate stems. In what 

 kind of fields is each grown, and how is it cared for ? 



77. How Water travels from Roots to Leaves. — We 

 have seen how the roots draw water, containing dissolved 

 mineral substances, from the soil. We have learned the 

 uses to which this water is put in the leaves. How does 

 it pass upward from the roots to the leaves? 



In every plant, extending continuously from the ends 

 of the roots to the leaves, are tiny tubes, which are more 

 or less connected. These are the water-carrying vessels, 

 and united with them are the food-carrying cells which we 

 shall study shortly. The two are joined in such a way as 

 to form strands, or threads, called fibro-vascular bundles. 



We noted in Section 45 that the common plants are 

 divided into two classes, the monocotyledons and the 

 dicotyledons. The stems of these two classes are very 

 different. In the monocotyledons the bundles described 

 above are scattered irregularly, either through the pith 

 as in the cornstalk, or through the walls of the hollow 

 stems, while in the dicotyledons, they are regularly 

 arranged in a circle or circles about the central pith. 



EXERCISE 34 



Object. — To study how the water travels from the 

 roots to the leaves. 



