THE STEM 43 



ing 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 more 

 or less horizontally. The privet may be taken as a 

 good example of the last class. On the upright grow- 

 ing shoots the leaves are arranged all round the stem, 

 so that we cannot say which is the upper and which 

 the lower side of the shoot. If, however, we examine 

 a shoot growing horizontally, we at once notice that all 

 the leaves are twisted 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. Still more careful examination, 

 however, particularly of the tip of the same branch, 

 will show that the leaves arise exactly as on the 

 upright-growing shoots, and twist later into their final 

 positions. Many creeping plants e.g., ground ivy, 

 creeping jenny, etc. also show very nice arrangements 

 to prevent the leaves shading one another, and in the 

 practical work great attention should be paid to them. 



Stems, like roots, often serve as storehouses of food. 

 The majority of the stems which serve as storehouses 

 grotf partially or entirely beneath the surface of the soil, 

 probably to protect the valuable stores of food they 

 contain from injury and cold. In general appearance 

 these underground stems resemble roots, indeed in some 

 cases it is difficult to distinguish them from roots. It 

 may, however, be taken as a general rule that a stem- 

 whatever use it may serve always bears leaves. The 

 examination of the examples given below will show us 



