A burl or burr 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.
Burrs on a tree trunk in Norfolk, England
Large burl on a spruce tree at Denali State Park, Alaska
A burled spruce log carved for use as a railing with built-in seats on a log cabin
A bowl made from a plum tree burl
Wood grain is the longitudinal arrangement of wood fibers or the pattern resulting from such an arrangement. It has various derived terms refer to different aspects of the fibers or patterns. Wood grain is important in woodworking and it impacts aesthetics.
The weathered trunk of a lodgepole pine tree showing an extremely spiral grain
typically figured red gum table
mountain ash floor, showing some fiddleback figure