40 FUNDAMENTALS OF AGRICULTURE. 



many leaflets of the leaf of locust, walnut, chinaberry, 

 etc. 



The Bud. In many plants we find the leaves com- 

 ing out of buds when they start out in the spring. A 

 bud contains the young leaves, tightly wrapped and 

 folded, and may be surrounded for protection by thick 

 or thin scales, which are themselves only modified 

 leaves. 



Kinds of Stems. The stem may be short, as in 

 those plants whose leaves form a cluster at the surface 

 of the ground or may be much elongated, as in the big 

 trees of California attaining a height of about 400 

 feet. Although the usual habit of a stem appears to 

 be upright growth, yet there are many exceptions. 

 They may twine around other objects for support, as 

 in the hop or morning glory, or trail on the ground. 

 Some plants, like the strawberry, may send out stems 

 along the surface of the ground which take root here 

 and there, forming clusters of leaves at those points; 

 these eventually becoming new plants. Such stems are 

 called runners. In some plants stems are produced 

 in a similar way but entirely underground, coming to 

 the surface at intervals and producing new plants. 

 Such stolons are produced by Bermuda and Johnson 

 grass, Solomon's seal, golden rod and many other 

 plants. When an underground stem becomes en- 

 larged to store up food it is called a tuber. The most 

 familiar example is the Irish potato. Tubers can be 

 distinguished from enlarged roots by the presence of 

 buds (or eyes) and leaves (usually reduced to small 

 scales, or entirely lacking). Both of these are lack- 

 ing on true roots. 



Structure of Stems. On cutting a stem across it is 

 found usually to have the following structure. At the 

 outside is a thicker or thinner layer, the bark or cor- 

 tex, the outer part of which may be alive or may be 

 made up of a thick layer of dead cork cells. Inside 

 the bark is the woody portion and in the center is the 

 pith. Between the wood and the bark is a thin layer 



