BUDS 157 



Roots from Stems. — Roots may develop from branches which are 

 subterranean or which rest upon the surface of the ground or are high 

 above it. The latter may descend and enter the ground, fix themselves 

 to a neighboring body for sustenance or support, or both, or extend 

 into the atmosphere. They may even turn and enter a diseased or 

 decaying portion of their own plant. They normally develop from the 

 node only, but may develop from any other part or even from leaves. 



Buds. — An undeveloped stem or branch, or the partially developed 

 summit of one, is a Bud or Gemma. The bud may be in a process of 

 continuous development of its lower elements into mature phytomers, 

 with the continuous production of a new growing point, or it may 

 pass into a resting state between successive seasons of growth. In 

 the latter case it undergoes special modifications (b in Figs. 447, 448, 

 and 450). Its outer leaves become developed previous to the resting 

 stage, but not as foliage leaves. They become modified instead in 

 various directions as to form, proportions, relative position, append- 

 ages, and exudations, to fulfil the office of protection as scales, 

 and they subsequently fall away, never developing into foliage leaves. 

 When no such provision is made, the bud is commonly destroyed, with 

 more or less of the young stem tip near it, during the resting period. 

 Occasionally the bud is protected for a time by a special covering, formed 

 by the petiole of the subtending leaf. It is then called a Subpetiolar 

 Bud. 



