CHAPTER IV 



THE BEST OF THE HARDY CLIMBING 

 SHRUBS 



PERMANENT VINES FOR TRELLIS AND WALL THAT WILL 

 GIVE A SUCCESSION OF FLOWER TO LATE FALL 



ONE of the fundamental properties of the living 

 substance of plants and animals (protoplasm) 

 is irritability or sensitiveness — the power of 

 responding to external stimuli. The class of plants 

 under consideration here owes its origin to this pe- 

 culiar property, and the most casual among us may 

 derive both pleasure and instruction from observing 

 this irritability in operation. Twining stems and 

 other organs specially adapted for the purpose of 

 assisting plants to climb are very sensitive to con- 

 tact. Further, if the necessary contact or external 

 stimulus be denied the growth of many climbing 

 plants is retarded. For example, when the young 

 shoots of Pole Beans commence to elongate and cast 

 round as it were (nutate) for some support every 

 gardener and farmer knows that poles must be affixed 

 or the crop of beans will be a failure. In the forests 



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