What Is a Tree Burl?

A tree burl is most common in the redwood species but can form on any woody plant. The burl forms at the base of the tree where buds or shoots, sometimes called suckers, form from the original tree. Under normal conditions, the shoots don't extend from the burl. Instead the buds form into a mass known as a burl. Other burls form from damage to the tree by accidents or insects.

Physically, the burl looks like a swirl of wood grain features that have a distinctive look from the rest of the tree. For this reason, burls often are used in decorative wood crafts such as wood turning and furniture. Larger pieces are sanded and finished for use as table tops or other larger furniture pieces. Redwood burls are sometimes sold as curiosity pieces that form plant shoots if left in water.

Some redwood burls are acquired illegally in unprotected forests. The removal of the burl from a living tree can lead to the death of the tree. Purchase any rare wood product only from a reputable dealer who can document the source of the product.

The redwood burl is actually a survival feature of the tree. The buds that form within the burl do not grow into shoots as long as the tree continues to live. If the tree dies naturally, by fire or by cutting, the burl becomes active and produces shoots that can grow into a new tree utilizing the root structure of the initial tree. This is a common propagation method for second or third generation woodlands where previous stands of redwood had been harvested.

Burls that form on trees above ground level don't function in the same way. These burls, which often look like bark-covered lumps, often form over some sort of damage to the tree. Often, multiple buds form creating a similar swirling grain pattern making this type of burl attractive to woodworkers. These burls may not directly kill a tree but are often associated with decreased tree vigor and health and may shorten the life of the tree.