BRANCHING OF STEMS 



167 



leaves are separated and better exposed to the light. If the in- 

 ternodes are short, as in the stem of the Dandelion, the leaves are 

 much crowded. Also in such plants as Beets, Radishes, Turnips, 

 and Lettuce the stem at first has short internodes and the leaves 

 are much crowded. 



On the ends of branches as well as in the axils of leaves, occur 

 the buds which have much to do with the growth of stems. The 

 stem elongates by the development . j. 



of new nodes and internodes from 

 the terminal buds, while branches 

 develop from the buds occurring in 

 the axils of the leaves. 



Branching of Stems. — Since 

 branches develop from the buds 

 located in the axils of the leaves, 

 the arrangement of branches tends 

 to follow the leaf arrangement. 

 Plants having two leaves at a node 

 and on opposite sides of the stem, 

 as in the Maple, tend to have 

 branches with the opposite arrange- 

 ment. Likewise, plants with leaves 

 occurring one at a node and on 

 alternate sides of the stem tend to 

 have the alternate arrangement of 

 branches, as Elms illustrate. 



The amount of branching varies 

 much among plants. Among herba- 

 ceous plants the stems of many of 

 the Grasses branch very little and 

 are called simple stems, while in 

 some plants, as Clover and Alfalfa 

 illustrate, there is very much branching. Branching reaches its 

 maximum among the trees, where often there is branching and 

 rebranching until the youngest branches are so numerous and 

 small, as in the Elms and Birches, that the tree may be some- 

 what brush-like in appearance. 



Branching is directly related to leaf display, for it not only 

 enables the plant to bear more leaves, but makes a better exposure 

 to sunlight possible. Branching is also related to flower and fruit 



Fig. 145. — Pines, showing 

 the exourrent type of stem. 

 After Fink. 



