Spruce Blobs

Woodworkers’ treasure.

Hints of spring are everywhere—an unusually warm afternoon that doesn’t require a parka, daylight that lasts past dinner time, an occasional whiff of earthy aroma along the trail. But Up North along the big lake there’s still plenty of ice and snow.  

A few days in a rustic cabin watching Lake Superior crash upon the rocks provided one last, dramatic dose of winter. Bundled up and walking along the trail I came across this knobby, blobby spruce tree. What the heck?

"It’s an injury. Broken limb, insect attack. Burl wood. Highly prized."

D. S. Brumitt

These bulbous growths are called burls. The scientific explanation is that they are caused by “hyperplasia, an abnormal proliferation of xylem production by the vascular cambium”.

Less scientifically, they are the result of a bacterium, a virus, a fungus, an insect, or an injury to a thin organic layer that makes cells increase and divide (hence tree rings)—and in response, they divide more rapidly and irregularly than normal. A tumor results.

The good news is that burls are not harmful to the tree. The other good news is that each burl has a unique interior pattern of knots, eyes, and swirls that cannot be replicated, making them highly desirable for luxury, artistic items—think decorative bowls, knife handles, even Rolls-Royce dashboards. Burls are naturally occurring and cannot be propagated or cultivated, and are pretty rare in nature.

Woodworkers, furniture makers, and luthiers, rejoice - there’s a forest full of burl wood in Minnesota.*

*Caution: Burl wood harvesting requires strict adherence to DNR regulations and permitting.