STEMS, THEIR FORMS AND FUNCTIONS 69 



KINDS OF BRANCHING 



Due to Leaf Arrangement. (Opposite and Alternate) The 

 branches of the stem originate as buds, which may be at the end 

 of the stem (terminal), or at the nodes, just above the leaves 

 (lateral). Insomuch as the branches always originate in this 

 way, it follows that if the leaves are opposite on the stem, the 

 branches will be opposite also, and if the leaves are alternately 

 arranged, the branches will arise in the same order. 



Examples of opposite arrangement are found in the ash, maple, 

 and horse-chestnut. The alternate type is represented by the elm, 

 oak, beech, and apple. 



In either case the chief object of the branch arrangement is to 

 expose the leaves uniformly to light and air. This is accomplished 

 in various ways, depending upon the development of the branch 

 buds, which influences the shape of the plant even more than the 

 leaf arrangement. 



Branching Due to Bud Development. Excurrent. If the termi- 

 nal bud keeps in advance of the lateral buds, a slender, cone- 

 shaped outline results, called the excurrent type, such as is shown 

 in the pines and spruces. 



Such trees have several advantages: 



1. They grow rapidly above their neighbors. 



2. Their slender, flexible tops offer little resistance to storms. 



3. They can grow close together and still let light down to the 



lower branches. 



4. Their lower branches can bend and shed snow easily. 



For these reasons the excurrent type is particularly adapted to 

 cold northern regions, where it is most frequently found. 



Deliquescent. If, on the other hand, the lateral buds equal or 

 exceed the terminal ones, the plant assumes a broad spreading 

 outline called the deliquescent type as shown by the elm, apple, 

 and oak. This type is very successful in competition with other 

 forms, because, even though it may start late, its broad top shades 

 and kills its neighbors. All plants which grow mixed with these 



