What Are Growths On The Side Of Trees?
| Updated: 10 Feb 2026
Mystery Hour Question
When I’m walking my dog in Richmond Park, I often notice huge growths on the side of trees. How are they formed?
Duncan, Richmond
Answer ** Definitive **
Name: Andrew, Newcastle
Qualification: Woodturner and woodworker
Answer: They are caused by a deformation in the grain when the tree is growing. It can be as a result of trauma or fungus growth.