A
burl or
bur or
burr (British English) is a tree growth in which the
grainIn speaking of wood the term grain refers to the alternating regions of relatively darker and lighter wood resulting from the differing growth parameters occurring in different seasons . The term is used in several ways. Perhaps most important is that in woodworking techniques...
has grown in a
deformedA deformity, dysmorphism, or dysmorphic feature is a major difference in the shape of body part or organ compared to the average shape of that part.Deformity may arise from numerous causes:*A Genetic mutation*Damage to the fetus or uterus...
manner. It is commonly found in the form of a rounded outgrowth on a
treeA tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
trunkIn botany, trunk refers to the main wooden axis of a tree that supports the branches and is supported by and directly attached to the roots. The trunk is covered by the bark, which is an important diagnostic feature in tree identification, and which often differs markedly from the bottom of the...
or
branchA branch or tree branch is a woody structural member connected to but not part of the central trunk of a tree...
that is filled with small knots from dormant buds.
A burl results from a tree undergoing some form of stress. It may be caused by an injury, virus or fungus. Most burls grow beneath the ground, attached to the
rootIn vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s as a type of
malignancyCancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
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
ropeA rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...
-like roots. Almost all burl wood is covered by
barkBark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
, even if it is underground.
InsectInsects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
infestation and certain types of
moldMolds are fungi that grow in the form of multicellular filaments called hyphae. Molds are not considered to be microbes but microscopic fungi that grow as single cells called yeasts...
infestation are the most common causes of this condition.
In some tree species, burls can grow to great size. The largest, at 26 feet (7.9 m) occur in Coast Redwoods (
Sequoia sempervirens) and can encircle the entire trunk; when moisture is present, these burls can grow new redwood trees. The world's second-largest burls can be found in
Port McNeill, British ColumbiaPort McNeill is a town in the North Island region of Vancouver Island, British Columbia, Canada with a population of 2,623 . Located on Vancouver Island's north-east shore on Queen Charlotte Strait, it was originally a base camp for loggers, Port McNeill became a settlement in 1936...
. One of the largest burls known was found around 1984 in the small town of
Tamworth, New South WalesTamworth is a city in the New England region of New South Wales, Australia. Straddling the Peel River, Tamworth, which contains an estimated population of 47,595 people, is the major regional centre for southern New England and in the local government area of Tamworth Regional Council. The city...
. It stands 6.4 ft (2 m) tall, with an odd shape resembling a trombone. In January 2009, this burl was controversially removed from its original location, and relocated to a public school in the central New South Wales city of Dubbo.
Burls yield a very peculiar and highly
figuredIn wood, figure refers to the appearance of wood, as seen on a longitudinal surface : a "figured wood" is not plain.The figure of a particular piece of wood is, in part, due to its grain and, in part, due to the cut, or to innate properties of the wood...
wood, prized for its beauty by many; its rarity also adds to its expense. It is sought after by furniture makers, artists, and
wood sculptorsWood carving is a form of working wood by means of a cutting tool in one hand or a chisel by two hands or with one hand on a chisel and one hand on a mallet, resulting in a wooden figure or figurine, or in the sculptural ornamentation of a wooden object...
. There are a number of well-known types of burls (each from a particular species); these are highly valued and sliced into
veneersIn woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
for furniture,
inlayMarquetry is the art and craft of applying pieces of veneer to a structure to form decorative patterns, designs or pictures. The technique may be applied to case furniture or even seat furniture, to decorative small objects with smooth, veneerable surfaces or to freestanding pictorial panels...
in doors,
picture frameA picture frame is a decorative edging for a picture, such as a painting or photograph, intended to enhance it, make it easier to display, or protect it.-Construction:...
s, household objects, automobile interior paneling and
trimWood trim, alternatively known as wood fascia, is fascia made of synthetic or varnished, natural wood, usually found on dashboards of luxury cars. First used in the '80s by Mercedes-Benz, they spread and soon other manufacturers were using them. Wood trim can be made from natural materials like...
, and
woodturningWoodturning is a form of woodworking that is used to create wooden objects on a lathe . Woodturning differs from most other forms of woodworking in that the wood is moving while a stationary tool is used to cut and shape it...
. The famous
birdseye mapleBird's eye is a type of figure that occurs within several kinds of wood, most notably in hard maple. It has a distinctive pattern that resembles tiny, swirling eyes disrupting the smooth lines of grain. It is somewhat reminiscent of a burl, but it is quite different: the small knots that make the...
of the sugar maple (Acer saccharum) 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
latheA lathe is a machine tool which rotates the workpiece on its axis to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation.Lathes are used in woodturning,...
because its grain is twisted and interlocked, causing it to chip and chatter unpredictably. This "wild grain" makes burl wood extremely dense and resistant to splitting, which made it valued for bowls, mallets, mauls and "beetles" or "beadles" for hammering chisels and driving wooden pegs.
Some burls are more highly prized than others, including ones from rural areas in central
MassachusettsThe Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
, northeast
ConnecticutConnecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...
, 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.
Burls are harvested with saws or axes for smaller specimens and timber felling chainsaws and tractors for massive ones.
Redwood Tree Burls
Many redwood trees have burls but they are not often harvested for use. Two things hinder the harvest of redwood burls, the first being that removing a burl can kill the tree. The second is their sometimes tremendous size; removing them can require the use of heavy equipment, which can be expensive and difficult to get to the tree.
Amboyna Burl
Amboyna burl is a particularly expensive type of burl, costing $18.00
b/fThe board-foot is a specialized unit of measure for the volume of lumber in the United States and Canada. It is the volume of a one-foot length of a board one foot wide and one inch thick....
to $22.00 b/f, much more than bigleaf maple burl, for example. It comes from Padauk trees (
PterocarpusPterocarpus is a pantropical genus of trees in the family Fabaceae, most of which yield valuable timber traded as padauk ; other common names are mukwa or narra...
spp.) of
Southeast AsiaSoutheast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. 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,
turneryWoodturning is a form of woodworking that is used to create wooden objects on a lathe . Woodturning differs from most other forms of woodworking in that the wood is moving while a stationary tool is used to cut and shape it...
,
cabinetsA cabinet is usually a box-shaped piece of furniture with doors or drawers for storing miscellaneous items. Some cabinets stand alone while others are built into a wall or are attached to it like a medicine cabinet. Cabinets are typically made of wood or, now increasingly, of synthetic...
,
veneerIn woodworking, veneer refers to thin slices of wood, usually thinner than 3 mm , that are typically glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors and parts of furniture. They are also used in marquetry...
, and
furnitureFurniture is the mass noun for the movable objects intended to support various human activities such as seating and sleeping in beds, to hold objects at a convenient height for work using horizontal surfaces above the ground, or to store things...
.