Striking Contrasts in Plums
The picture shows a blue stoneless plum growing on the same tree the Barnblood plum-the result, of course, of a grafting experiment, in which the Barnblood tree was the stock. Such anomalies are common enough in Mr. Burbank's orchard, but are always interesting.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 5 Chapter 5