A burl is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds. Insect infestation and certain types of molds are the most common causes of this condition, although other stresses can also promote burl formation, such as physical injury, or viral or fungal infection.
Most burls grow beneath the ground, attached to the roots as a type of malignancy that is generally not discovered until the tree dies or falls over. Such burls sometimes appear as groups of bulbous protrusions connected by a system of rope-like roots. Almost all burl wood is covered by bark, even if it is underground. In some tree species, burls can grow to great size. The largest, at 26 feet, occur in redwoods and can encircle the entire trunk. Burls yield a very peculiar and highly figured wood, prized for its beauty, strength, and rarity. It is sought after by furniture makers, artists, and wood sculptors.
There are a number of well-known types of burls (each from a particular species) that are highly valued and sliced into veneers for furniture, inlay in doors, picture frames, household objects, automobile interior paneling and trim, and woodturning. The famous birdseye maple of the sugar maple superficially resembles the wood of a burl but is something else entirely. Burl wood is very hard to work with hand tools or on a lathe because its grain is twisted and interlocked, causing it to chip and shatter unpredictably. This ‘wild grain makes the wood extremely dense and resistant to splitting, which made it valued for bowls, mallets, and mauls.
Some burls are more highly prized than others, including ones from rural areas in central Massachusetts, northeast Connecticut, and as far south as Philadelphia. Some resemble an explosion in which the grain grows erratically, and it is these burls that the artist prizes over all other types. These spectacular patterns enhance the beauty of wood sculptures, furniture, and other artistic productions. Amboyna burl is a particularly expensive type of burl, costing $300 per pound, much more than bigleaf maple burl, for example. It comes from padauk trees of Southeast Asia. Padauk trees are quite common but the burl is extremely rare. The amboyna is usually a deep red, although the more rare moudui burl is the same species but the color is from golden yellow to yellow-orange. The sapwood is creamy white with brown streaks. The common use for amboyna is interiors for luxury vehicles, turnery, cabinets, veneer, and furniture. Burls are harvested with saws or axes for smaller specimens and timber felling chainsaws and tractors for massive ones.
Because of their value, burls from ancient redwoods in National Parks in Western United States have recently been poached by thieves, including at Redwood National and State Parks. Poachers often cut off the burls from the sides of the trunks using chainsaws, which exposes the tree to infection and disease, or fell the entire tree to steal burls higher up. Because of risk of poaching, Jeff Denny, the state park’s redwood coast sector supervisor, encourages those buying burl to enquire where it came from and to ensure it was obtained legally. Legal acquisition methods for burl include trees from private land cleared for new development and from lumber companies with salvage permits.
The Daily Omnivore 