The Sultan Plum
This is another variety produced by crossing the Burbank and the Satsuma. It is very different in appearance from the Prize plum shown previously, but it has qualities of its own that highly commend it, and it was early introduced. It has maintained its popularity through the decades, and is now widely grown.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 5 Chapter 1