BURBANK'S HORTICULTURAL NOVELTIES 213 



In some cases, the history of the succeeding crosses may 

 still be traced, although of course the selection has steadily 

 eliminated some characters and augmented others. But 

 wherever the pedigree is historically known, the explanation 

 of the different characters of a hybrid and their reduction 

 to those of the single parental types is, of course, more reliable 

 than in the ordinary cases. As an illustration, Burbank has 

 described the pedigree of his Alhambra plum. It is a com- 

 bination of seven distinct parents, some of which are of 

 American, some of Japanese and others of European origin. 

 Among the latter some are probably the offspring of old and 

 long- forgotten crosses, thus making the pedigree still more 

 complicated. Each generation requires about three years, 

 the seedlings being grafted in their first summer on old trees 

 and thereby being brought to blossom at a very early period 

 of their life. The whole pedigree includes, by this manage- 

 ment, only thirteen years. The initial cross was made 

 between the Kelsey plum and Prunus Pissardi, an ornamen- 

 tal tree with a dark purplish foliage but without edible fruit. 

 The offspring of this cross was fertilized with the pollen of 

 the flowers of the French prune, and the threefold hybrid 

 thus improved was destined for still further combinations. 

 For these, in the meantime, hybrids had been prepared in 

 order to bring the desirable characters of two new forms into 

 the strain by means of a single cross. First a hybrid of 

 Simoni and triflora was used, and the offspring obtained 

 in this way was fertilized with the pollen of Americana x 

 nigra, bringing up the total number of the constituents 

 to seven. Of course, the offspring of this last cross was 

 utterly variable and among it the Alhambra was chosen as 

 the best. 



Summing up the main lines of this historical sketch, we 

 may put them into the following pedigree : 



