Burl: Difference between revisions
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{{short description|Deformed tree outgrowth}} | {{short description|Deformed tree outgrowth}} | ||
{{other uses}} | {{other uses}} | ||
[[File:Growth on tree trunk - geograph.org.uk - 724687.jpg|right|thumb|200px|Burrs on a tree trunk in [[Norfolk]], England]] | [[File:Growth on tree trunk - geograph.org.uk - 724687.jpg|right|thumb|200px|Burrs on a tree trunk in [[Norfolk]], England]] | ||
A '''burl''' (American English) or '''burr''' (British English) is a tree growth in which the [[wood grain|grain]] has grown in a [[Deformity|deformed]] manner. It is commonly found in the form of a rounded outgrowth on a tree [[Trunk (botany)|trunk]] or [[branch]] that is filled with small [[Knothole|knots]] 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 | A '''burl''' (American English) or '''burr''' (British English) is a tree growth in which the [[wood grain|grain]] has grown in a [[Deformity|deformed]] manner. It is commonly found in the form of a rounded outgrowth on a tree [[Trunk (botany)|trunk]] or [[branch]] that is filled with small [[Knothole|knots]] 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]], a greatly abnormal proliferation of [[xylem]] production by the [[vascular cambium]]".<ref> Smith, Kevin T. 2012. The biology of burls. Bark. Issue 3(2012): 6. [Published by Massachusetts Tree Wardens and Foresters Association]. https://research.fs.usda.gov/treesearch/42292 </ref><ref>{{cite web | title=The Mystery of Tree Burls | date=6 January 2022 | url=https://extension.unh.edu/blog/2022/01/mystery-tree-burls }}</ref> | ||
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]] of burl specimens and damaging the trees in the process poses a problem in some areas. | 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]] of burl specimens and damaging the trees in the process poses a problem in some areas. | ||
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A burl results from a tree undergoing some form of [[stress (biology)|stress]]. It may be caused by a virus, [[Mold (fungus)|fungus]]<ref>{{Cite web |title=What's a "Burl" and Why Is There One on My Tree? |url=https://www.thespruce.com/tree-burl-7153353 |access-date=2024-05-13 |website=The Spruce |language=en}}</ref> or ''[[Agrobacterium tumefaciens]]'' entering the plant through an injury. Most burls grow beneath the ground, attached to the roots as a type of [[Cancer|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 (botany)|bark]], even if it is underground. | A burl results from a tree undergoing some form of [[stress (biology)|stress]]. It may be caused by a virus, [[Mold (fungus)|fungus]]<ref>{{Cite web |title=What's a "Burl" and Why Is There One on My Tree? |url=https://www.thespruce.com/tree-burl-7153353 |access-date=2024-05-13 |website=The Spruce |language=en}}</ref> or ''[[Agrobacterium tumefaciens]]'' entering the plant through an injury. Most burls grow beneath the ground, attached to the roots as a type of [[Cancer|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 (botany)|bark]], even if it is underground. | ||
In some tree species, burls can grow to great size. The largest, at {{Convert|26|ft|m|0|abbr=on}}, occur in coast redwoods (''[[Sequoia sempervirens]]'') 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]].<ref>https://www.timescolonist.com/local-news/port-mcneill-moving-beloved-burl-to-new-more-visible-location-8226172</ref> | In some tree species, burls can grow to great size. The largest, at {{Convert|26|ft|m|0|abbr=on}}, occur in coast redwoods (''[[Sequoia sempervirens]]'') 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]].<ref>{{cite web | title=Port McNeill moving beloved burl to new, more visible location | date=8 February 2024 | url=https://www.timescolonist.com/local-news/port-mcneill-moving-beloved-burl-to-new-more-visible-location-8226172 }}</ref> | ||
==Use== | ==Use== | ||
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==Working the wood== | ==Working the wood== | ||
The prized "{{vanchor|burr maple}}" is not a species of a maple, but wood from a maple's burl (burr). | The prized "{{vanchor|burr maple}}" is not a species of a maple, but wood from a maple's burl (burr). | ||
[[Birdseye maple]] of the sugar maple (''[[Acer saccharum]]'') superficially resembles burr maple, but the causes of the bird's eye [[Figure_(wood)|figure]] are unknown.<ref>{{cite web |title=""Birds Eyes" in Maple: are indentations in the grain" |url=https://www.fpl.fs.usda.gov/documnts/pdf1930/pillo30b.pdf |access-date=July 9, 2025 |website=Forest Products Laboratory (USDA) |language=en}}</ref> | |||
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 burl wood extremely dense and resistant to splitting, which made it valued for bowls, mallets, [[splitting maul|maul]]s and "beetles" or "beadles" for hammering chisels and driving wooden pegs.<ref>Sloane, Eric (1973). ''A Museum of Early American Tools''. New York: Ballantine Books. pp. 28–32. {{ISBN|0-486-42560-6}}.</ref> | 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 burl wood extremely dense and resistant to splitting, which made it valued for bowls, mallets, [[splitting maul|maul]]s and "beetles" or "beadles" for hammering chisels and driving wooden pegs.<ref>Sloane, Eric (1973). ''A Museum of Early American Tools''. New York: Ballantine Books. pp. 28–32. {{ISBN|0-486-42560-6}}.</ref> | ||
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* {{cite journal |author1=White, PR |author2=Millington, WF |title=The distribution and possible importance of a woody tumor on trees of the white spruce, Picea glauca |journal=Cancer Research |volume=14 |issue=2 |pages=128–34 |date=February 1954 |pmid=13126948 |url=http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=13126948}} | * {{cite journal |author1=White, PR |author2=Millington, WF |title=The distribution and possible importance of a woody tumor on trees of the white spruce, Picea glauca |journal=Cancer Research |volume=14 |issue=2 |pages=128–34 |date=February 1954 |pmid=13126948 |url=http://cancerres.aacrjournals.org/cgi/pmidlookup?view=long&pmid=13126948}} | ||
* {{cite journal |author=White, PR |title=A Tree Tumor of Unknown Origin |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=44 |issue=4 |pages=339–44 |date=April 1958 |pmid=16590202 |pmc=335423 |jstor=89803 |bibcode=1958PNAS...44..339W |doi=10.1073/pnas.44.4.339|doi-access=free }} | * {{cite journal |author=White, PR |title=A Tree Tumor of Unknown Origin |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=44 |issue=4 |pages=339–44 |date=April 1958 |pmid=16590202 |pmc=335423 |jstor=89803 |bibcode=1958PNAS...44..339W |doi=10.1073/pnas.44.4.339|doi-access=free }} | ||
* {{cite journal |last=Zalasky |first=Harry |year=1975 |title=Low-temperature-induced cankers and burls in test conifers and hardwoods |journal=Canadian Journal of Botany |volume=53 |issue=21 |pages=2526–35 |doi=10.1139/b75-277}} | * {{cite journal |last=Zalasky |first=Harry |year=1975 |title=Low-temperature-induced cankers and burls in test conifers and hardwoods |journal=Canadian Journal of Botany |volume=53 |issue=21 |pages=2526–35 |doi=10.1139/b75-277 |bibcode=1975CaJB...53.2526Z }} | ||
==External links== | ==External links== | ||
Latest revision as of 08:20, 25 September 2025
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A burl (American English) or burr (British English) 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. 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, a greatly abnormal proliferation of xylem production by the vascular cambium".[1][2]
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 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[3] or Agrobacterium tumefaciens entering the plant through an injury. 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 Script error: No such module "convert"., occur in coast redwoods (Sequoia sempervirens) 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.[4]
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 in doors, picture frames, household objects, automobile interior paneling and trim, musical instruments, and woodturning.
Working the wood
The prized "Template:Vanchor" is not a species of a maple, but wood from a maple's burl (burr). Birdseye maple of the sugar maple (Acer saccharum) superficially resembles burr maple, but the causes of the bird's eye figure are unknown.[5]
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 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.[6]
Poaching
Because of the value of burls, ancient redwoods in national parks in the Western United States have recently been poached by thieves for their burls, including at Redwood National and State Parks.[7] 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.[7] 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.[7]
Gallery
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A bowl made from a plum tree burl
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A giant burl near Solduc Falls in the Olympic National Park
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A large spruce burl on display at the University of Alberta
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A longitudinal section through a larch burl from Ayrshire, Scotland
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Multiple burls on an ancient cypress tree at the Beijing Temple of Confucius in China
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A park ranger inspects a redwood tree illegally cut to obtain a burl, Redwood National Park, California
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Burls on Sitka spruces, Olympic National Park, Washington, US
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Burl near Palfau,
in central Austria -
Burls Pithecellobium dulce
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Burls on hollow trunk, Samanea saman
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See also
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References
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- ↑ Smith, Kevin T. 2012. The biology of burls. Bark. Issue 3(2012): 6. [Published by Massachusetts Tree Wardens and Foresters Association]. https://research.fs.usda.gov/treesearch/42292
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- ↑ Sloane, Eric (1973). A Museum of Early American Tools. New York: Ballantine Books. pp. 28–32. Template:ISBN.
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Further reading
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