Yet Another Shirley
Once a flower manifests a tendency to vary, there seems to be no limit to the range of its variations. It would be hard to say just what combination of hereditary factors in the germ plasm of the original Shirley led to its peculiar departure from the traditions of its tribe. But man's selective judgment enabled these submerged color factors to make themselves manifest, as they doubtless would not have done without his aid; with the result that a strikingly modified flower was produced in the course of a few generations.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 9 Chapter 4