The External Features of Stems 119 



Contents 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 develop on the 

 sides of the young stem within the bud. These are called branch 

 buds, because when they grow they produce a new leaf-bearing 

 branch. Some buds, as for example many of those on the maples 

 and elms, contain the beginnings of flowers (flower buds or fruit 

 buds). Other buds, like some of those of the catalpa and the 

 horse-chestnut, contain both leaves and a flower cluster (mixed 

 buds). Bulbs are really a special underground form of bud, and 

 they are similar in structure to other buds. 



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 develop 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 (Fig. 87) among trees. Plants with 

 strong lateral buds usually branch continually and become bushy 

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

 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 season's growth. The fol- 

 lowing year the lateral buds develop, and the long shoot becomes 

 highly branched. As these lateral branches bear the flowers and 

 produce them abundantly only once, we can promote flowering 

 in these roses by trimming away each year all but the long, 

 unbranched shoots. In many other shrubs, as spirea, barberry, 

 and privet, a few strong lateral buds at the surface of the soil 



