Skin Texture of a Plum
The texture of the skin may have a very important bearing on the commercial value of a fruit. At the left is shown a plum with very thick skin, which will withstand shipping; at the right, a thin-skinned fruit, which may be valuable for home consumption, but which cannot be sent to distant markets.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 5 Chapter 6