Editing Burl

{{short description|Deformed tree outgrowth}}
{{other uses}}
{{More footnotes|date=June 2011}}

[[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 “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>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.

==Description==
[[File:Fatburl.jpeg|thumb|right|Large burl on a spruce tree at [[Denali State Park]], Alaska]]

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>

==Use==
[[File:Burlrailingseats.JPG|thumb|left|A burled spruce log carved for use as a railing with built-in seats on a log cabin]]
Burls yield a very peculiar and highly [[figure (wood)|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, [[Marquetry|inlay]] in doors, picture frames, household objects, automobile interior paneling and trim, musical instruments, and [[woodturning]].

==Working the wood==
The prized "{{vanchor|burr maple}}" is not a species of a maple, but wood from a maple's burl (burr).
The famous [[birdseye maple]] of the sugar maple (''[[Acer saccharum]]'') superficially resembles burr maple, but it 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 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>

==Poaching==

Because of the value of burls, ancient [[redwood]]s in national parks in the [[Western United States]] have recently been poached by thieves for their burls, including at [[Redwood National and State Parks]].<ref name="nytimes1">{{cite news |first=Patricia Leigh |last=Brown |date=April 8, 2014 |title=Poachers Attack Beloved Elders of California, Its Redwoods |url=https://www.nytimes.com/2014/04/09/us/poachers-attack-beloved-elders-of-california-its-redwoods.html |work=The New York Times}}</ref> 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.<ref name="nytimes1"/> 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.<ref name="nytimes1"/>

==Gallery==
<gallery mode="packed">
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]]
File:Spruce burl at University of Alberta.jpg|A large spruce burl on display at the [[University of Alberta]]
File:Burr section on Larch.JPG|A longitudinal section through a larch burl from [[Ayrshire]], Scotland
File:Broussins sur un cyprès.jpg|Multiple burls on an ancient cypress tree at the [[Beijing Temple of Confucius]] 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]], California
File:Spruce Burl trail, Kalaloch Beach, Washington 02.jpg|Burls on [[Picea sitchensis|Sitka spruces]], Olympic National Park, Washington, US
File:Palfauer Wasserlochklamm Ohrwaschlbaum 2012-08 Naturdenkmal 975.jpg|Burl near [[Palfau]],<br />in central Austria
File:Quercus-petraea-30-11-2009-001.jpg|Burl on a sessile oak<br />(''[[Quercus petraea]]'')<br />Brohmer Bergen, Germany
File:北京中山公园 千年古树 树瘤.jpg|One of several thousand-year-old [[Platycladus]] with many burls in [[Zhongshan Park (Beijing)|Zhongshan Park]], west of [[Tian'anmen]]
File:金龜樹 Pithecellobium dulce 20210907092835 01.jpg|Burls ''[[Pithecellobium dulce]]''
File:雨豆樹 Samanea saman 20210914102518 01.jpg|Burls on hollow trunk, ''[[Samanea saman]]''
</gallery>

==See also==
{{Portal|Trees}}
* [[Canker]]
* [[Forest pathology]]
* [[Gall]]
* [[Guksi]]

==References==
{{reflist}}

==Further reading==
* {{cite book |last=Corbett |first=Stephen |year=2006 |title=The Illustrated Professional Woodworker |location=London |publisher=Anness Publishing |isbn=978-0-681-22891-7}}
* {{cite journal |last=Funk |first=A. |year=1982 |title=Therrya canker of spruce in British Columbia |journal=Canadian Journal of Plant Pathology |volume=4 |issue=4 |pages=357–61 |doi=10.1080/07060668209501277|bibcode=1982CaJPP...4..357F }}
* {{cite journal |last=James |first=Susanne |year=1984 |title=Lignotubers and Burls: Their Structure, Function and Ecological Significance in Mediterranean Ecosystems |journal=Botanical Review |volume=50 |issue=3 |pages=225–66 |jstor=4354037 |doi=10.1007/BF02862633|bibcode=1984BotRv..50..225J |s2cid=20759935 }}
* {{cite book |last=Powers |first=Steven S. |year=2005 |title=North American Burl Treen: Colonial & Native American |location=Brooklyn |publisher=S. Scott Powers Antiques |isbn=978-0-9760635-0-6}}
* {{cite book |last=Rankin |first=William Howard |year=1918 |chapter=Mistletoe Burl and Witches'-Broom |chapter-url=https://books.google.com/books?id=M4AqAQAAMAAJ&pg=PA214 |pages=214–5 |title=Manual of Tree Diseases |oclc=1652501}}
* {{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 |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}}

==External links==
*[https://www.youtube.com/watch?v=otuaDMiRLJ8 Video footage of tree burrs]

[[Category:Antiques]]
[[Category:Furniture]]
[[Category:Trees]]
[[Category:Wood]]
[[Category:Wood-related terminology]]