LUTHER BURBANK 



For two or three generations, the flowers 

 seemed fixed. I could see no change whatever; no 

 tendency to break into new forms. I attempted 

 to hybridize the two species of bidens, but did not 

 succeed, so it was necessary to depend upon selec- 

 tion alone. The plants were grown in large quan- 

 tities. After several years, slight variations 

 appeared; and then, as in so many cases, the ten- 

 dency to variation became somewhat accentuated. 



I became convinced that the black dahlia and 

 other species of bidens are well worth cultivating, 

 and that some other valuable tuberous flowering 

 plants could be developed from them that would 

 be welcomed by flower lovers in general. 



But other engagements made it impossible for 

 me to carry the experiments beyond the early 

 stages. 



And as to the matter of crossing the bidens with 

 the dahlia, in which I had been especially inter- 

 ested, the result was altogether negative. 



Repeated efforts failed to fertilize either species 

 with the pollen of the other. 



Notwithstanding the outward similarity of the 

 plants, it would appear that their racial strains 

 have diverged beyond the point of ready com- 

 mingling. Still it is possible that a more extensive 

 series of experiments might have met with better 

 results, and further efforts along the same line are 



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