30 TRINCirLES AND PEACTICE OF PRUNING 



(1) Rapid extension of resting buds into shoots which 

 bear no other parts than those already in the buds them- 

 selves. In this group belong many north temperate trees 

 and shrubs, among which beech and pine may be taken 

 as typical, the former having a segmented, the latter an 

 unsegniented shoot. In spring the beech bud gradually 

 swells, and at first presents a fairly general extension of 

 the internodes. Soon the bud has doubled its original 

 length, at which time the method of extension may best 

 be noted. Beginning at the basal node, it will be seen 

 that each internode in turn becomes successively most 

 acti\'e, so that the terminal internodes are the last to 

 extend rapidl_v. The pine shows a similar development 

 except that, ha^'ing an unsegmented stem, the most ac- 

 tively extending part moves gradually forward in a more 

 uniform manner than in the case of the beech. Apples 

 and pears present much the same method as the beech. 



(2) Some trees and shrubs, such as willow and lilac, 

 normally develop more leaves than those wintered over 

 in the resting bud, so that the total number of nodes and 

 internodes at the end of the growing season is larger than 

 the numbers represented in the buds. The peach may 

 sometimes develop lea\-es, nodes and internodes in this 

 wav', though it perhaps generally de\'elops as described 

 under class one. This phenomenon is probably more 

 common in young trees than in older ones. For instance, 

 old trees of the cottonu'ood or necklace poplar (Popidns 

 monUifcra) may de\'elop no more lea\'es, nodes and inter- 

 nodes, than were contained in the resting bud; young 

 ones may develop three, four or even more times as many. 

 From such instances it is concluded that conditions, such 

 as age, cnxironment and character of season, may ac- 

 count for the differences. 



The secondary growth of shoots, especially of fruit 

 trees, must not be confounded with the normal phenomena 

 discussed above. Such growth usually occurs during a 



