Seedling Plum with Stem Attached
This fruit has a stone like that of ordinary plums. The cut fruit shows the attachment of the stem to the stone. Stone and stem serve somewhat the purpose of the beams and girders of a building. The question of the firmness of attachment between the stem and stone is sometimes an important one. Prunes should be so loosely attached to the stem that they fall of their own weight when ripe. Yet the attachment must not be so loose that the fruit will fall before it is ripe.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 2 Chapter 4