132 



PRACTICAL COURSE IN BOTANY 



145- Terminal and axillary buds. Notice the large bud 

 at the end of a twig of hickory, sweet gum, beech, cotton- 

 wood, etc. This is called the terminal bud because it ter- 

 minates its branch. Notice the scars left by the leaves of 

 the season as they fell away, and look for small buds just 

 above them. These are lateral, or axillary, buds, so called 

 because they spring from the axils of the leaves. How 

 many leaves did your twig bear? What 

 difference in size do you notice between 

 the terminal and lateral buds? 



146. The leaf scars. Examine the leaf 

 scars with a hand lens, and observe the 

 number and position of the little dots in 

 them. Ailanthus, varnish tree, sumach, 

 tr and China tree show these very distinctly. 

 tr They are called leaf traces, and mark the 

 points where the fibrovascular bundles 

 from the leaf veins passed into the stem. 

 FIG. 149. winter Look on the bark, or epidermis, for lenticels. 



twig of sugar maple : 

 t, terminal bud ; ax, 

 axillary buds ; Is, leaf 

 scars ; tr, leaf traces ; 



I, lenticels ; rs, ring of 

 scars left by bud scales 

 of preceding season. 



147. Bud scales and scars. Notice the 

 , hard scales by which the winter buds 

 are covered in most of our hardy trees and 

 shrubs. Remove these from the terminal 

 one of your specimen, and notice the ring 

 of scars left around the base. Look lower down on your 

 twig for a ring of similar scars left from last year's bud. 

 Is there any difference in the appearance of the bark above 

 and below this ring ? If so, what is it, and how do you ac- 

 count for it ? Is there more than one of these rings of scars 

 on your twig, and if so, how many ? How old is the twig 

 and how much did it grow each year ? Has its growth been 

 uniform, or did it grow more in some years than in others ? 

 148. Arrangement and use of the scales. Notice the 

 manner in which the scales overlap so as to " break joints," 

 like shingles on the roof of a house. Where the leaves are 

 opposite, the manner of superposition is very simple. Re- 



