Q. Why do some trees shed their bark?
This process of shedding bark is known as exfoliating. It is a natural process in which bark peels off a tree in thin flakes, scales, or layers and exposes a new bark layer. Exfoliating bark is a feature of some trees with thin bark. As these trees grow and their trunk diameter expands, the outer layer of bark splits and is replaced by new bark underneath.
Some of the most popular trees that have exfoliating bark are crape myrtles, sycamore, and river birch. You will also see this characteristic on bald cypress, Chinese elm, and eastern red cedar.
Exfoliating bark is foreign to many people; gardeners sometimes think it's a problem. It is not. These trees are genetically designed for this process. You should never help the peeling process by pulling loose bark. Let the tree naturally shed the bark.
Bark exfoliation is an interesting feature that many people like. The process starts sometime after the trees start to grow in the spring and then is prominent through winter, giving eye-catching detail to the trees. For many species, bark shedding tends to be more predominant every other year. Exfoliation takes place in drake elms after 4-5 years, when they start to significantly expand their trunk size.
An added aspect of exfoliating bark is that sometimes the inner bark is a different color than the outer layer. Two of the most striking examples of trees with contrasting bark colors are Natchez crape myrtle, with its cinnamon colored bark, and Drake Chinese elm, with orange bark.
Exfoliating bark is interesting to see, but eye appeal is not the main reason that it exists. It's a survival tool that eliminates unwanted pests such as scales and other insects. Exfoliation also helps trees rid themselves of hitchhikers such as bacteria, fungi, lichens and mosses.
For tips on a variety of gardening topics, see our Plant Information Guides.
- Courtesy of NYBG Plant Information Service