244 LUTHER BURBANK 



FORCING THE RHUBAEB 



It is well known that the ordinary rhubarb 

 may be forced in the greenhouse, and made to 

 produce out of season by first freezing the roots. 

 Curiously enough, after this treatment, the root 

 develops its stalk, granted the right conditions 

 of soil, almost equally well in the dark. 



Mention is made of this possibility of forcing 

 the rhubarb by inducing abnormal conditions 

 lest a statement of the earlier chapter in which 

 the habits of the new variety are explained 

 should be misinterpreted. 



I referred there to the impossibility of chang- 

 ing the habits of the ordinary rhubarb, and per- 

 manently extending its period of bearing, by 

 merely altering the conditions of cultivation. It 

 is of course possible to cause almost any plant 

 to germinate out of season by greenhouse treat- 

 ment. Such treatment, however, has no in- 

 fluence on succeeding generations. 



The plant caused to grow out of season 

 merely responds to the abnormal surroundings 

 in which it is placed, and will immediately revert 

 to the habits of its tribe when placed under nor- 

 mal conditions. 



But the crimson Winter Rhubarbs in all the 

 perfected varieties produce their main crop in 



