This refers to willow which has been deformed while growing. At spots where branches begin to grow, the wood grows "away from" the new branch, causing a depression in the shape of the "diamond" on a deck of playing cards. The wood is white and the diamonds red so they make the most beautiful hiking sticks, walking sticks and canes in the world. I call it "Pure Art by Mom Nature." An encyclopedia of information about Diamond Willow sticks at http://www.sticksite.com/
Diamond Willow grows, typically, in wet areas where the mosquitos are the worst. In Northern Canada, it seems, are the best ones.