LUTHER BURBANK 



According to the estimates of the botanist, the 

 dahlias have fairly close relationship with plants 

 of the genus Bidens. Indeed, a familiar species of 

 the genus, known as Bidens atrosanguinea, a 

 tuberous variety with dark purple flower, is often 

 spoken of as the black dahlia. Its tubers and foli- 

 age strongly suggest the common dahlia in minia- 

 ture. 



For four or five years I worked extensively with 

 this so-called black dahlia, not only by way of 

 improving the flower itself, but also in the attempt 

 to hybridize it with the dahlia proper. 



I succeeded by selective breeding in enlarging 

 the flower to about twice its original size, in mak- 

 ing the petals much rounder and fuller, in adding 

 extra petals, and in changing the color of the petals 

 from the usual dark purplish crimson to a light 

 crimson approaching scarlet and in a few cases 

 to a pale pink approaching white. The bush itself 

 was also made more compact. 



All these changes were produced by selection 

 and re-selection, working constantly toward the 

 new colors desired, and toward increase of the 

 size of flower, and modification of form. 



The species worked with was a Mexican form. 

 There is an aquatic form with large, brilliant, yel- 

 low flowers, closely related to the species known 

 in the east as "pitchforks." 



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