Burl
（重定向自Burr wood）
![Burs on a tree trunk in Norfolk County, England](/Images/godic/202501/02/Growth_on_tree_trunk_-_geograph.org.uk_-_7246873045.jpg")
![](/Images/godic/202501/02/Broussins_sur_un_cyprès3045.jpg")
![Arquitectura del tallo.](/Images/godic/202501/02/Vastago_23045.JPG")
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A burl (American English) or bur or burr (used in all non-US English speaking countries) 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.