LUTHER BURBANK 



How does heredity explain the observed fact 

 that some of these are dwarfs that can by no 

 process of urging be made to attain anything 

 like the average stature of walnuts in general, 

 whereas others, sprung from nuts grown on the 

 same stalks, are giants that surpass even their 

 hybrid parent, not to mention their moderate- 

 sized grandparents. The fact of this diversity is 

 unquestionable. It affords a surprise to all who 

 inspect the trees of this strangely diversified 

 fraternity. 



But how explain it? 



A clue to the explanation is gained when we 

 learn that the California walnut, which, it will be 

 recalled, was a parent form in each of the hybrid 

 strains, is a tree showing great variability in the 

 matter of size when growing in a state of nature. 

 In the northern and central parts of California 

 it is usually a large spreading tree, often with 

 gracefully drooping limbs. But farther to the 

 south it becomes a mere shrub, and on the moun- 

 tains and hills about Los Angeles it is only a bush. 

 The nut diminishes in size correspondingly until, 

 in Texas and Mexico, it is scarcely larger than 

 a pea. 



"When growing still further to the south, in 

 New Mexico and Texas, the black walnut is some- 

 times classified as a different species. 



[158] 



