TYPES OF STEMS. 



379 



740. Opening of the buds. — When the >oung shoot begins to 

 grow in the spring, tlie bud-scales are forced ap>art or open of 

 their own accord. During the young condition the shoot is very 

 soft and brittle, and also pos.sesses a very thin, little cutinized 

 epidermis. In this condition it is especially hable to mechanical 



Fig. 431. 

 Opening buds of hickory. 



injury and to injury from drying out. We find, therefore, a 

 tendencv for the inner bud-scales to elongate during vernation, 

 thus forming a tube around the dehcate tissue much like the 

 opening out of a telescope. The }'oung lca-\'es and internodes 



