A Burl on a Prunus serotina (wild cherry tree) 

A Burl on a Prunus serotina (wild cherry tree) near the west pond at Clary Gardens. Burls are deformed growths on trees that creates a beautiful variation in the grain pattern and are highly valued by woodworkers. Burls can be found underground on roots, but also on the trunks of trees as seen here. The general consensus is that burls are formed where biological injury has occurred, from insect or fungus.