CHAPTER VII 



THE DECLINE OF GROWTH AND THE REST- 

 PERIOD 



Annual plants usually perish soon after maturing their 

 seed. In other plants, a certain period of vital activity is 

 followed by one in which growth gradually declines until 

 it almost or entirely ceases. In woody plants, the cells 

 become thickened and a part of the rudimentary leaves 

 change to bud-scales, which inclose the growing point 

 (127). In deciduous trees and shrubs, the chlorophyll and 

 starch, with most of the potash and phosphoric acid con- 

 tained in the leaves are withdrawn into the woody parts 

 (126), while the leaves themselves are detached and fall. 

 The root-hairs also die in many, if not all, plants. The 

 leaves of many trees and shrubs assume striking colors 

 as they approach maturity. In perennial herbs, the nutri- 

 tive matters in the foliage and stem are withdrawn to the 

 underground parts. A period of almost complete repose 

 ensues, during which the plant, owing to the dormant 

 condition of its protoplasm, is able to endure without harm 

 extremes of temperatures or dryness that would be fatal 

 in its active state. 



170. Cessation of growth. — Growth ceases in many 

 trees and shrubs earlier than is often supposed. Most 

 orchard and forest trees of mature age grow little, if any, 



104 



