LUTHER BURBANK 



fornia black walnut was hybridized with the black 

 walnut from the eastern part of the United States. 

 These two trees are more closely related species, 

 and have diverged relatively little. Doubtless the 

 time when they had a common ancestor is rela- 

 tively recent as contrasted with the period when 

 that common ancestor branched from the racial 

 stem that bore the Persian and Japanese walnuts. 



Yet the differences between the walnuts of the 

 eastern and western parts of America are sufficient 

 to introduce a very strong tendency to variation. 



Indeed, the result of crossing these species was 

 in some respects scarcely less remarkable than 

 that due to the crossing of the Persian walnut with 

 the black walnut of California. 



In this case, as in the other, the hybrid tree 

 proved to have extraordinary capacity for growth. 

 Indeed, I have never been able to decide as to 

 which of the hybrids is the more rapid grower. 

 But in the matter of nut production, the discrep- 

 ancy was nothing less than startling. For, whereas 

 the first-generation paradox walnut produced, as 

 we have seen, only occasional nuts, the hybrid 

 between the two black walnuts it was named the 

 Royal proved perhaps the most productive nut 

 tree ever seen. 



I have elsewhere cited a tree, sixteen years of 

 age, that produced twenty large apple boxes full 



[46] 



