314 Plant Physiology 



in the periblem in a manner very similar to the fundament 

 of the leaf. 



182. The resting bud. Aside from the method of more 

 or less continuous leaf development in the bud which has 

 been stated to be the rule during the growth period of 

 annuals, it is necessary to consider more particularly this 

 phenomenon with respect to certain trees. In a majority 

 of trees the shoot axis is terminated during the summer or 

 early autumn by a resting bud. This bud is merely a 

 very short leaf axis protected by bud scales, the latter 

 being structures homologous with leaves or leaf parts. 

 As a matter of fact, this terminal bud may be more or less 

 completely differentiated in the early portion of the 

 summer, but it does not necessarily present the appear- 

 ance of a resting bud until midsummer or later. 



Growth within the so-called resting bud proceeds very 

 slowly, or may entirely cease, for several months during 

 the winter. The following spring, with the return of 

 favorable conditions for growth, there is generally a rapid 

 unfolding of the leafy shoot, or of the cluster of leaves or 

 flowers. It must not be understood, however, that this 

 resting bud cannot be forced into more or less immediate 

 growth, or that it is necessarily formed so early in the 

 season. As a matter of fact, it appears that adventitious 

 buds may arise and develop shoots during a single season, 

 and that water shoots may form no terminal bud until 

 completing a season of growth more or less equivalent to 

 that of an annual. 



183. Types of stem elongation. Wholly apart from 

 the exceptional cases referred to, the method of elongation 

 of the shoot, or bud axis, in woody plants is diverse, and 



