LUTHER BURBANK 



for their sustenance from subterranean sources in 

 regions where the surface of the country is that of 

 the desert; economizing this for long seasons of 

 drought which may follow. 



Hereditary Traits 



These new races of spineless cactus are of many 

 varieties, in token of their varied ancestry. 



In producing them I followed my usual custom 

 of securing material from every available source. 



The main supply came, naturally, from the arid 

 regions of the Southwest; the original home of the 

 cactus. But I received also plants from Minnesota, 

 Montana, Dakota, New England, Missouri, and 

 Colorado, South America, North and South Africa, 

 and regions around the Mediterranean. It could 

 not be known at the outset just what crosses would 

 be most effective, and so experimented on every 

 species on which I could lay hands. I poUenized the 

 giant Tunas with pollen of the little trailing cactus, 

 and with such inconspicuous cousins of the giant 

 as the little hardy Opuntia vulgaris. 



There were several small more or less spineless 

 species available, and others that produced a com- 

 paratively small crop of spines, and of course it 

 was recognized from the outset that these must be 

 our main reliance. Just as the little French par- 

 tially stoneless plum had been the foundation for 

 building the stoneless plums and prunes of to-day, 



[178] 



