They have an attraction, these lumpy knobs on trees. Several times I’ve stared up at a tree in a forest with a magnificent lumpy knob, and, after admiring it, wondered if it was the next to be stolen. The theft of maple burls have been reported on the news in Oregon and with redwood burls in California.
Burl wood is wavy and without pattern and valued in woodworking. It is made into exquisite furniture, bowls, and jewelry.
While out there in the woods staring at burls I’ve wondered, what made them?
Arborists say these unusual growths are caused by pathogenic stress from a virus, fungus or bacteria that sabotages the growth of that area, causing undifferentiated, callus-like growth. Often it is not clear which pathogen creates the burl as they are often long gone when the burl reaches any size.
Next, staring at the tree in the woods, I’ve wondered, what about our bonsai with burls? That grotesque and beautiful growth on the trunk, is that OK? Am I right to worry about that? Will the tree perish from some unfortunate burl accident?
Apparently not. The burl does not weaken or shorten the lifespan of trees, according to arborists. It only makes them more interesting. It is only if we cut into a living burl that we may damage a tree.
Fascinating burl on an elm bonsai which makes it unique.