The mustard is a plant to which the ordinary amateur gardener pays very little attention. "Mustard is mustard." would probably be his comment, and it would not occur to him that the plant is one having any particular interest from the standpoint of the would-be plant developer. In point of fact, however, there Is a good range of variation between different mustards, and Mr. Burbank has seized on these variations for material to work conspicuous improvements, notably as regards the amount and quality of the pungent principle for which the mustard seed is prized.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 7 Chapter 5