32 



BUDS. 



[section 4. 



the Rose, Blackberry, and Raspberry. That is, these shoots are apt to 

 grow all summer long, until stopped by the frosts of autumn or some other 

 cause. Consequently they form and ripen no terminal bud protected by 

 scales, and the upper axillary buds are produced so late in the season that 

 they have no time to mature, nor has their wood time to solidify and ripen. 

 Such stems therefore commonly die back from the top in winter, or at 

 least all their upper buds are small and feeble ; so the growth of the suc- 

 ceeding year takes place mainly from the lower axillary buds, which are 

 more mature. 



63. Deliquescent and Excurrent Growth. In the former case, and 

 wherever axillary buds take the lead, there is, of course, no single main 

 stem, continued year after year in a direct line, but the trunk is soon lost 



in the branches. Trees so formed commonly have rounded or spreading 

 tops. Of such trees with deliquescent stems, — that is, with the trunk 

 dissolved, as it were, into the successively divided branches, — the common 

 American Elm (Fig. 80) is a good illustration. 



64. On the other hand, the main stem of Firs and Spruces, unless de- 

 stroyed by some injury, is carried on in a direct line throughout the whole 

 growth of the tree, by the development year after year of a terminal bud : 

 this forms a single, uninterrupted shaft, — an ezcurrent trunk, which can- 

 not be confounded with the branches that proceed from it. Of such spirt/ . 

 or spire-shaped trees, the Firs or Spruces are characteristic and familiar 

 examples There are all gradations between the two modes. 



Fia. 80. An American Elm, with Spruce-trees, and on the left Arbor Vita. 



