STEMS 



71 



86. Annual, Biennial, and Perennial Plants. — Annual 

 plants are those which live but one year, biennials those 

 which live two years 

 or nearly so. 



Some annual plants 

 may be made to live 

 over winter, flower- 

 ing in their second 

 summer. This is true 

 of winter wheat and 

 rye among cultivated 

 plants. 



Perennial plants live for a series of 

 years. Many kinds of trees last for 

 centuries. The Californian giant redwoods, or Sequoias 

 (Fig. 32), which reach a height of over 300 feet under 

 favorable circumstances, live nearly 2000 years ; and some 



Fig. 3G. — a Portion of 



the Brancli of Fig. 35. 



(Natural Bize.) 



Fig. 37. —Twigs and 



Branclies of the 



Birch. 



monstrous cypress trees found in Mexico were thought by 

 Professor Asa Gray to be from 4000 to 5000 years old. 



