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Question and Answer ArticleA Closer Look at Tree Burls

Ugly, problematic, creepy or beautiful? Depends on who you ask.
By Amanda Williams
Published: August 1, 2014
red pine tree tumors burls
Photo by Amanda Hansen
Burl grain tree
The grain of a tree burl exhibits rare and natural beauty.
Photo by
Q: The red pine outside the bedroom at my cabin has many large "tumors" growing on its trunk. By day, it looks deformed in a cool sort of way. But at night, the shadows it throws are absolutely terrifying! What are those things, and are they harmful to the tree?

A: The "tumors" on your tree are called burls. They're unnatural swellings on the trunk of a tree that usually start when tree tissue is provoked by fungi, insects laying eggs in the sap, or bacteria causing an irritation. The burl grows with the tree, but the growth ring inside the burl shows it grows faster that the rest of the tree.

The swelling won't kill the tree, but it does weaken it. And that makes the tree more susceptible to other harmful diseases which may eventually kill the tree. Burls take a long time to grow and only affect a small percentage of trees.

Once disregarded by timber cutters and left to rot on the forest floor, burls are now in demand by woodcarvers for their spectacular grain patterns and natural beauty. The furniture made from burls is valued for its uniqueness. Your tree could be a diamond in the rough.

Take advantage of the terrifying shadows it throws this Halloween. Tell ghost stories in the bedroom by candlelight – it will add the perfect effect.
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