A burl (American English) or burr (British English) is a tree growth in which the

grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...

has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree

trunk Trunk may refer to: Biology * Trunk (anatomy), synonym for torso * Trunk (botany), a tree's central superstructure, and the stem of woody plants * Trunk of corpus callosum, in neuroanatomy * Elephant trunk, the proboscis of an elephant Comput ...

branch A branch, also called a ramus in botany, is a stem that grows off from another stem, or when structures like veins in leaves are divided into smaller veins. History and etymology In Old English, there are numerous words for branch, includ ...

that is filled with small

knots A knot is a fastening in rope or interwoven lines. Knot or knots may also refer to: Other common meanings * Knot (unit), of speed * Knot (wood), a timber imperfection Arts, entertainment, and media Films * ''Knots'' (film), a 2004 film * ''Kn ...

from dormant buds. Burl formation is typically a result of some form of stress such as an injury or a viral or fungal infection. More scientifically, a burl is “the result of

hyperplasia Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of Tissue (biology), organic tissue that results from ...

, a greatly abnormal proliferation of

xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...

production by the

vascular cambium The vascular cambium is the main growth tissue in the stems and roots of many plants exhibiting secondary growth, specifically in dicots such as buttercups and oak trees, gymnosperms such as pine trees, as well as in certain other vascular ...

”. Burls yield a very peculiar and highly figured wood sought after in woodworking, and some items may reach high prices on the wood market.

Poaching Poaching is the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set against the huntin ...

of burl specimens and damaging the trees in the process poses a problem in some areas.

Description

A burl results from a tree undergoing some form of stress. It may be caused by a virus,

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

or ''

Agrobacterium tumefaciens ''Agrobacterium tumefaciens'' (also known as ''Rhizobium radiobacter'') is the causal agent of crown gall disease (the formation of tumours) in over 140 species of eudicots. It is a rod-shaped, Gram-negative soil bacterium. Symptoms are cause ...

'' entering the plant through an injury. Most burls grow beneath the ground, attached to the roots as a type of

malignancy Malignancy () is the tendency of a medical condition to become progressively worse; the term is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not ...

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 Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...

, even if it is underground. In some tree species, burls can grow to great size. The largest, at , occur in coast redwoods (''

Sequoia sempervirens ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995: 606–607 is the sole living species of the genus ''Sequoia (genus), Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast ...

'') and can engirdle the entire trunk; when moisture is present, these burls can grow new redwood trees. One of the world's largest burls can be found in

Port McNeill, British Columbia Port McNeill is a town in the North Island region of Vancouver Island, British Columbia, Canada on Vancouver Island's northeast shore, on Queen Charlotte Strait. Originally a base camp for loggers, it became a settlement in 1936. It was named ...

Use

Burls yield a very peculiar and highly figured wood, prized for its beauty 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); these are highly valued and sliced into veneers for furniture,

inlay Inlay covers a range of techniques in sculpture and the decorative arts for inserting pieces of contrasting, often colored materials into depressions in a base object to form Ornament (art), ornament or pictures that normally are flush with the ...

in doors, picture frames, household objects, automobile interior paneling and trim, musical instruments, and

woodturning Woodturning is the craft of using a wood lathe with hand-held tools to cut a shape that is symmetrical around the axis of rotation. Like the potter's wheel, the wood lathe is a mechanism that can generate a variety of forms. The operator is kno ...

Working the wood

The prized "" is not a species of a maple, but wood from a maple's burl (burr). The famous

birdseye maple Bird's eye is a type of figure that occurs within several kinds of wood, most notably 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 i ...

of the sugar maple (''

Acer saccharum ''Acer saccharum'', the sugar maple, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is native to the hardwood forests of eastern Canada and the eastern United States. Sugar maple is best known for being the p ...

'') superficially resembles burr maple, but it is something else entirely. Burl wood is very hard to work with hand tools or on a

lathe A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, threading and turning, with tools that are applied to the w ...

, because its grain is twisted and interlocked, causing it to chip and shatter unpredictably. This "wild grain" makes burl wood extremely dense and resistant to splitting, which made it valued for bowls, mallets,

maul A maul may refer to any number of large hammers, including: * War hammer, a medieval weapon * Post maul, a type of sledgehammer * Spike maul, railroad hand tool * Splitting maul, heavy wood-splitting tool resembling both axe and hammer People * A ...

s and "beetles" or "beadles" for hammering chisels and driving wooden pegs.Sloane, Eric (1973). ''A Museum of Early American Tools''. New York: Ballantine Books. pp. 28–32. .

Poaching

Because of the value of burls, ancient

redwood Sequoioideae, commonly referred to as redwoods, is a subfamily of Pinophyta, coniferous trees within the family (biology), family Cupressaceae, that range in the Northern Hemisphere, northern hemisphere. It includes the List of superlative tree ...

s in national parks in the

Western United States The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is List of regions of the United States, census regions United States Census Bureau. As American settlement i ...

have recently been poached by thieves for their burls, including at

Redwood National and State Parks The Redwood National and State Parks (RNSP) are a complex of one United States national park and three California state parks located along the coast of northern California. The combined RNSP contain Redwood National Park, Del Norte Coast Red ...

. 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 the risk of poaching, Jeff Denny, the state park's redwood coast sector supervisor, encourages those buying burl to inquire 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.

Gallery

File:doggerel bowl.jpg, A bowl made from a plum tree burl File:Giantburl.jpg, A giant burl near Solduc Falls in the

Olympic National Park Olympic National Park is a national park of the United States located in Washington, on the Olympic Peninsula. The park has four regions: the Pacific coastline, alpine areas, the west-side temperate rainforest, and the forests of the drier e ...

File:Spruce burl at University of Alberta.jpg, A large spruce burl on display at the

University of Alberta The University of Alberta (also known as U of A or UAlberta, ) is a public research university located in Edmonton, Alberta, Canada. It was founded in 1908 by Alexander Cameron Rutherford, the first premier of Alberta, and Henry Marshall Tory, t ...

File:Burr section on Larch.JPG, A longitudinal section through a larch burl from

Ayrshire Ayrshire (, ) is a Counties of Scotland, historic county and registration county, in south-west Scotland, located on the shores of the Firth of Clyde. The lieutenancy areas of Scotland, lieutenancy area of Ayrshire and Arran covers the entirety ...

, Scotland File:Broussins sur un cyprès.jpg, Multiple burls on an ancient cypress tree at the

Beijing Temple of Confucius Beijing Temple of Confucius () is the second-largest Confucian temple in China, after the one in Confucius's hometown of Qufu. History The Temple of Confucius in Beijing was built in 1302 during the reign of Temür (Emperor Chengzong) of the Y ...

in China File:Redwood NP Burl Cut May 2013 (2).jpg, A park ranger inspects a redwood tree illegally cut to obtain a burl,

Redwood National Park The Redwood National and State Parks (RNSP) are a complex of one List of national parks of the United States, United States national park and three List of California state parks, California state parks located along the coast of northern Cali ...

, California File:Spruce Burl trail, Kalaloch Beach, Washington 02.jpg, Burls on Sitka spruces, Olympic National Park, Washington, US File:Palfauer Wasserlochklamm Ohrwaschlbaum 2012-08 Naturdenkmal 975.jpg, Burl near

Palfau Palfau is a former municipality in the district of Liezen in the Austrian state of Styria. Since the 2015 Styria municipal structural reform The Styria municipal structural reform (German: ''Steiermärkische Gemeindestrukturreform'') was a lo ...

,
in central Austria File:Quercus-petraea-30-11-2009-001.jpg, Burl on a sessile oak
(''

Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Welsh oak, Cornish oak, Irish oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an un ...

'')
Brohmer Bergen, Germany File:北京中山公园千年古树树瘤.jpg, One of several thousand-year-old

Platycladus ''Platycladus'' is a monotypic genus of evergreen coniferous trees in the cypress family Cupressaceae, containing only one species, ''Platycladus orientalis'', also known as Chinese thuja, Oriental arborvitae, Chinese arborvitae, biota or Orienta ...

with many burls in

Zhongshan Park Zhongshan Park () is a common name for Chinese parks, in honour of Sun Yat-sen, better-known in Chinese as Sun Zhongshan, who is considered by many to be the " Father of modern China". Currently there are more than 40 Zhongshan Parks in China, and ...

, west of

Tian'anmen The Tiananmen , also Tian'anmen, is the entrance gate of the Forbidden City imperial palace complex and Imperial City in the center of Beijing, China. It is widely used as a national symbol. First built in 1420 during the Ming dynasty, Ti ...

File:金龜樹 Pithecellobium dulce 20210907092835 01.jpg, Burls ''

Pithecellobium dulce ''Pithecellobium dulce'', commonly known as Manila tamarind, Madras thorn, monkeypod tree or camachile, is a species of flowering plant in the pea family, Fabaceae, that is native to the Pacific Coast and adjacent highlands of Mexico, Central A ...

'' File:雨豆樹 Samanea saman 20210914102518 01.jpg, Burls on hollow trunk, ''

Samanea saman ''Samanea saman'' is a species of Flowering plant, flowering tree in the pea family, Fabaceae, now in the Mimosoideae, Mimosoid clade and is native to Central and South America. It is often placed in the genus ''Samanea'', which by yet other aut ...

References

External links

Video footage of tree burrs
Antiques Furniture Trees Wood Wood-related terminology