Stems and Their External Features 109 



Kinds of buds. Every bud contains the growing point of a 

 stem. In addition, most buds contain the beginnings of 

 foliage leaves ; that is, the leaves have already begun to de- 

 velop on the sides of the young stem within the bud. Some 

 buds, as for example many of those on the maples and elms, 

 contain the beginnings of flowers. Other buds, like some of 

 those of the catalpa and the horse-chestnut, contain both 

 leaves and a flower cluster. Bulbs are really a special under- 

 ground form of bud, and they are similar in structure to other 

 buds. We shall consider bulbs when we come to the study 

 of underground stems. 



Bud development and plant form. Buds which occur at 

 the ends of stems are called terminal buds ; those which occur 

 at the nodes are called lateral buds. This classification is 

 useful because only a part of the buds on a stem ever de- 

 velop and because the form of a plant depends on which set 

 of buds develops more freely and grows more rapidly. In 

 most plants, the terminal bud simply extends a stem or 

 branch ; the lateral buds produce new branches. Plants 

 with very strong terminal buds tend to become columnar in 

 form, like the large, unbranched sunflowers of the garden or 

 like the spruce and palm among trees. Plants with strong 

 lateral buds tend to branch continually and to become bushy 

 in form, like the lilac and hydrangea. There are all grada- 

 tions between these extremes in the development of the 

 terminal and lateral buds, and in the resulting plant forms. 



In many roses the shoots from the base of the stem develop 

 only through their terminal buds the first year. The shoot is 

 thus extended to great length by the first season's growth. 

 The following year the lateral buds develop, and the long 

 shoot becomes highly branched. As these lateral branches 



