Two Inches in Diameter in One Year
The cross section of a Paradox walnut trunk pictured above shows the annual rings of the tree, or its yearly growth. The photograph is made exact size, and it will be noted that some of the markings are an inch apart, thus showing that the tree increased in diameter two full inches within the year.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 2 Chapter 5