A burl (British "burr") is a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds. Burls are the product of a cambium. The famous birdseye maple superficially resembles the wood of a burl but is something else entirely. Burls yield a very peculiar and highly figured wood. There are a number of famous burls (each from a particular species); these are highly valued and used as veneers in furniture, picture frames, household objects, automobile interior paneling and trim, and woodturning. In some tree species, burls can grow to great size. Some of the largest occur in redwoods (Sequoia sempervirens); when moisture is present, these burls can grow new redwood trees. The world's largest and second-largest burls can be found in Port McNeill, British Columbia. One of the largest burls known to man was found around 1984 in the small town of Tamworth, Australia. It stands 6.4 ft tall with an odd growth resembling a trombone.
Gallery
 Maple burl, not to be confused with bird's-eye maple. |
 A giant burl near Solduc Falls in Olympic National Park. |
 An unusually large spruce burl on display at the University of Alberta. |
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 A burl the size of a refrigerator on the trunk of a Coast Redwood. |
Burl woods, sought after by artists such as furniture makers and wood sculpters, are the result of a tree that undergoes some form of stress. It may be environmental or introduced by man. Most burls grow beneath the ground, attached to the roots as though a type of malignancy that is not discovered until the tree dies, or falls over. The burl sometimes looks like bulbous partil round pieces of small to large and heavy pieces often connected by a system of rope-like roots. Almost all burl wood is covered by bark even though it is underground. Insect infestation and certain types of mold infestation are the most common causes of this condition. Some burls are more highly prized than others and this is due to the fact that the burl has the rings of the host tree and inherits this . But some burls seem to get an explosion of sorts which causes the grain to grow helter-skelter and it is these burls that the artist prizes over all other types. These spectacular patterns are what is made into wood sculptures, furniture, and other artistic endeavors.To find burls there are a variety of methods. Many redwood trees have them, but there are two things that hold back the harvest of redwood burls. one is that the removal of the burl can cause the death of the tree. The other is that the burls of redwoods can be of tremendous size, and at abnormal depths, so the removal of these burls require heavy equipment, which can be expensive and at times unable to get to the area of the tree due to the terrain.
