Nice, beautiful trees in our landscape just seem to make everything look better. But sometimes our trees can fall victim to disease or environmental damage so it’s always a good idea to keep an eye on our trees to watch for something unusual. There are, however, a couple of non-threatening growths that are not that unusual to find on or in our trees. The first one we are going to talk about is known as a burl.

Burls are irregularly shaped, round, bumps, or bulges on trees. While there is some disagreement on what causes burls to grow, they are an abnormal growth of the tree which can be caused by either a virus, bacterial infection, fungi, or insects.

Burls are prized by woodworkers for their unique grain patterns, so if there were a way to commercially produce burls, you can bet someone would be doing it. While burls don’t seem to have any negative impact on the tree, removing a burl from a healthy tree will result in an open wound on the tree, leaving it vulnerable to disease and decay. So, if you have a tree in your landscape that has a burl, just enjoy its uniqueness. It will definitely be a conversation starter and now you know what to call them.

Woodworkers use burl wood to produces bowls or veneers. Sometimes this wood is used to make unique musical instruments like guitars. If you are curious, just do a quick internet search and you’ll see many examples of the wood from burls being used for a variety of purposes.

Another non-threatening growth you might find on your trees is something called lichen. Lichen is a curious organism because it exists as a combination of two unrelated organisms: an algae and a fungus. When they combine in a mutually beneficial way, they behave as a single organism known as a lichen.

In this relationship, the algae takes care of the photosynthesis to provide energy while the fungus gathers the water and minerals. When working together they make up what is called a lichen thallus. Color and growth patters enable the cohabitants to be classified into a variety of lichens.

The lichen you have probably seen on trees are grey green in color, but lichens can also be found in colors of orange, yellow, black, or dark blue. Lichens live on the surface of the tree without penetrating the tree, so they do not cause any problems for the tree.

Lichen growth is somewhat limited in shade, but they can grow quite rapidly on dead or dying trees due to the increased sunlight that gets through with the absence of leaves. Oftentimes when a dead branch falls from a tree, you find an out-cropping of lichen on the branch.

However, lichens can also grow on rocks, soil, or any other sunny surface. If fact, you may have seen lichens growing on old tombstones.

So, now you know. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Ryan Armbrust, Kansas Forest Service, Bugwood.org