USES OF STEMS. 43 



the above-ground portion, the root only being 

 below ground. This, however, is not always 

 the case, and a few of the more important 

 exceptions will be considered later. 



USES OF STEMS. 



1. One of the most important functions 

 of the stem of a plant is to support the leaves 

 and display them to the air and light in the 

 best possible manner for the work they have 

 to do. Careful observations should be made 

 of the arrangement of the leaves on (1) upright 

 growing plants, (2) climbers against walls, 

 trees, etc., (3) plants which trail along the 

 ground, (4) plants in which some of the 

 branches are upright whilst others lie horizon- 

 tally. The lime tree may be taken as a good 

 example of the last class. On the upright 

 growing shoots the leaves are arranged all 

 round the stem, so that we cannot speak of an 

 upper and lower side to the branch. If how- 

 ever we examine a shoot growing horizontally, 

 we at once notice that all the leaves are twist- 

 ed round to one side, so that on looking from 

 above we see only the upper sides of leaves, 

 whilst from beneath only the under sides. 

 Here, then, we have apparently a distinct 

 upper and lower side to the branch, but still 

 more careful examination, particularly of the 



