STEMS 375 



Has the water risen and colored this cross section as it did the cross 

 section of the corn stalk? 



Stems vary greatly in the positions they assume. Some 

 rise firmly erect from the root, like the oak and the pine; 

 some cling to supports, like the grape and the ivy ; some 

 twine around supports, like the bean; some creep upon 

 the ground, like the strawberry; some grow in 

 the form of a thickened bulb like the onion 

 (Figure 113) ; some, like the cacti, assume a 

 fleshy, leaflike, though leafless form; some, like 

 the nut grass, Johnson grass, and witchgrass, FlGURE 113 

 grow underground and send up shoots, and some 

 stems store up food underground in tubers, like the potato 

 (Figure 114), from which the next year's 

 plant may grow. 



Notwithstanding all the diversity shown 

 by the stem, its principal functions are 

 to support the leaves, so that they will 

 best be exposed to the light, and to con- 

 duct the food solutions from the root to the leaves. The 

 part of the stem through which the cell sap flows was seen 

 in Experiments 115 and 116. 



There are two great types of stems, one represented by 

 the corn stalk and palm and the other by the willow, sun- 

 flower, and bean. On account of the structure of the seeds 

 these are called, respectively, monocotyledonous (one seed 

 leaf) and dicotyledonous (two seed leaves). That these 

 differ greatly in their appearance was seen in Experiments 

 115 and 116, where the two kinds of stems were com- 

 pared. It was also found in these experiments that, in 

 the first, the red colored water that took the place of 

 the sap rose in the fibrous bundles scattered through the 



