University of Maryland Extension

Burls - Trees and Shrubs

burl

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A burl is a large woody, rounded swelling, usually found on a tree trunk. Burls can obtain a diameter up to 3 feet and may have many buds or sprouts. "Burl wood" is prized for its unusual grain pattern. The grain of the wood swirls around each bud trace, forming interesting patterns in the wood.

The cause of most burls cannot be explained. They may develop as a result of insects, bacteria, fungi, mistletoes, or environmental injury, such as freeze damage. Sprouts arising from the burl may be pruned off, otherwise, no treatment is necessary. Removal of the burl may damage the tree and is not recommended.

large burl
Burls can obtain a diameter up to 3 feet and may have many buds or sprouts.

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