My Grand-Dad was a master German Dowser, Lived in a small town in NY! Well as I say a German Master Dowser and with his willow branch he could find where the bee hives were located in the barns at old farms etc. He had several willow branches and even had one with a silver coin in the end and would find lost silver coins.
I have found water and other materials I wanted to be found. Actually it is not the name of the branch, it is the flexibility of the branch, or any other material that are flexible to do its job.
I've never used one but I know extensively how to make one.
You can use any real soft and flexible wood: boxelder, willow, bass wood, anything real flexible.
Cut it in the shape of a Y with the upper branches of of the Y about 12 inchs and the bottom about 3 inches. The diameter of the stick should be about that of a pencil. And that's it. I'll leave the application up to you.