42 



COLLEGE BOTANY 



grown by tke wood of the stem and cause what is usually known 

 as "bird's-eye" wood. They are known as "dormant buds." 

 Shrubby plants in which a very large percentage of the buds grow 

 are frequently used for hedges. This hedge character is very 

 prominent in such plants as the privet, the osager-orange and 

 the barberry. 



In most of our trees and shrubs the shoots reach their full 

 length'in a very short time, and the remainder of the growing 



Fig. 20. — Bud, dissected to show scales and leaves. 



season is devoted to thickening and hardening ; this is knovpi as 

 " definite " annual growth. This is characteristic of most of our 

 trees and shrubs in the iSTorth Temperate regions. In some other 

 plants the shoots continue to lengthen and new leaves axe pro- 

 dueled tkroughout the season; as in the case of sumach, spice 

 bush, roses and lilacs. This is known as " indefinite " annual 

 growth. The terminal buds and tips of the shoots of this type 

 of plant are frequently killed by frost. This maizes it necessary 

 for one or more of the lateral buds to develop as terminal buds 

 the following season (Fig. 21). 



