A tree burl is an abnormal, rounded outgrowth that forms on the trunk, branch, or root of a tree. This structure is highly sought after in the woodworking industry because of the unique and complex wood grain it contains. When cut and polished, the wood from a burl displays intricate patterns that are impossible to find in regular timber, making this biological anomaly extremely valuable.
The Biology Behind the Burl
Burls are essentially the tree’s defensive response to stress, often appearing as dense, rounded protrusions. The stress can originate from various sources, including fungal or bacterial infections, insect infestations, or physical trauma to the bark. This abnormal growth is a type of hyperplasia, involving an abnormal proliferation of xylem production by the vascular cambium, the layer responsible for producing wood.
The tree attempts to isolate the irritant, triggering the activation of numerous dormant buds beneath the bark. This results in rapid, chaotic cell division that forms a mass of disorganized tissue, creating the characteristic lumpy exterior. Since the formation is a response to an unpredictable stress event, burls are naturally rare and their internal structure is never the same twice. This growth prevents wood fibers from aligning in the straight, parallel fashion typical of normal lumber.
Unique Wood Grain and Figure
The disorganized cell structure within the burl produces a figure densely packed with swirls, loops, and contorted grain. Unlike the straight grain of typical wood, this chaotic growth pattern gives the wood its exceptional aesthetic appeal. This unique appearance is highly valued by artisans and woodworkers.
The most distinctive features are the presence of “eyes,” or pin knots, which result from countless aborted dormant buds trapped within the mass. When sliced, these features create mesmerizing, three-dimensional patterns that appear to shimmer under a finish. Popular examples include “bird’s-eye” patterns, which look like small, circular eyes scattered throughout the wood, and the complex, flowing swirls found in species like Mappa Burl. The wood’s rarity is compounded because the actual quality of the figure remains hidden until the burl is cut open, making it a natural gamble.
Primary Commercial Applications
The highly figured nature of burl wood commands a premium in luxury markets. The most common and economically significant application for large burls is the production of fine wood veneers. These thin slices allow the spectacular figure to be spread across a large surface area, maximizing the value of the limited resource.
These veneers are extensively used for interior trim in high-end luxury vehicles, such as dashboards, door panels, and console faces. Walnut burl is a predominant choice for this application, signaling elegance and luxury in automotive design. Beyond automotive use, solid pieces of burl are highly prized for small, specialized craft items where the figure is the sole focus. These items include:
- Custom knife and gun handles
- Tobacco pipes
- Jewelry boxes
- Decorative woodturning art
Factors Determining Market Price
The market price for a raw tree burl is determined by several specific variables that influence both its usability and desirability. The species of the tree is a primary factor, with certain types, such as Redwood, Walnut, and Amboyna burl, consistently fetching higher prices due to established demand and a reputation for superior figure.
Size and weight also directly correlate with price, as larger burls have a higher potential yield, particularly for cutting large veneer sheets or table slabs. However, the internal stability of the burl is equally important; a burl with significant internal rot, voids, or cracks will be heavily discounted, regardless of its size, because a large percentage of the wood will be unusable. Finally, the location and ease of harvest play a role in the final cost to the buyer. Burls found deep in remote forests require expensive logging and transportation, which is factored into the final price.