A Grafted Walnut Tree
The selected varieties of walnuts do not breed true from the seeds; so it is necessary to graft them, in making commercial orchards, just as in the case of the orchard fruits. Here is a typical grafted specimen, growing in the back yard of Mr. Burbank's home in Santa Rosa.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 11 Chapter 2