346 LUTHER BURBANK 



be necessary before the quality of fragrance 

 is combined with satisfactory qualities of size 

 and form and color. But there is every proba- 

 bility that these combinations will be effected in 

 due course, and that races of dahlias which com- 

 bine all the qualities for which the flower is now 

 prized, with the added quality of pleasing 

 aroma, will be available. 



WIDER HYBRIDIZATION ATTEMPTED 



We have seen that the experiments through 

 which the original wild dahlias were transformed 

 into georgeous double flowers of a character- 

 istic type utilized the principle of hybridization 

 at all stages. In my own experiments I have 

 attempted to extend the principle, not merely to 

 all the flowers of the genus, but also to those of 

 allied genera. 



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 atrosan- 

 guinea, a tuberous variety with dark purple 

 flowers, is often spoken of as the black dahlia. 

 Its tubers and foliage strongly suggest the com- 

 mon dahlia in miniature. 



For several years I worked extensively with 

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



