David Robson Extension Educator, Springfield Extension Center, University of Illinois
Yard & Garden
A bit about the beauty of bark
During the dog days of summer bark is unappreciated
The dog days of summer make us wish for the coolness of fall and winter, which of course, then makes us wish for the warmth of summer come January.
In a twisted fashion, the dog days tend to make me think about bark. Yes, you can “boo.”
Bark is essentially the skin of trees and shrubs, though a tomato gets somewhat woody toward the end of the season. So do green peppers and many of the vining crops. Geraniums and lantana kept for years will develop something that approaches bark.
You can look at that outer coating as a protection, just like our skin. Remove the bark and the plant dies. Damage it, it might die. Or not.
Bark varies as much as the plants themselves.
Some bark can be thick and furrowed, such as Amur Cork tree (Phellodendron) and walnuts (Juglans) while others may be smooth like cherries (Prunus). Some can be smooth and furrowed, sort of like an elephant’s skin. Think of the grossly underplanted beech (Fagus) trees.
Bark is often an identifying characteristic of the tree.
The above-mentioned walnut will flake into walnut-colored pieces under the gray bark. Most other bark is the same color on the outside as it is inside.
Sycamore (Platanus) bark may not be that easily identified close to the ground, but if you look at the edges of the branches, you’ll see the white color. Horticulturist call it a 65 miles-per-hour tree as you can identify the tree going down the interstate that fast.
Ash (Fraxinus) trees, being plagued by the Emerald Ash Borer, have a distinct diamond pattern on mature trees. Once you see the pattern, you never forget it.
Our native persimmon (Diospyros), one of two native fruit trees, has a square pattern to the bark, which stands out easily on the pole-like trunks in the woods. Unfortunately, the other native fruit, Pawpaw (Asimina), has indistinct bark, unless you are another pawpaw.
Many of the birch (Betula) trees have exfoliating or peeling bark such as the river birch. Some may have smooth white bark, though the white poplar (Populus) also has white bark. The poplar has white on the underside of the leaves which helps distinguish it from the birches.
Our state tree, the white oak (Quercus alba), doesn’t get its name from the color of the bark, though most of the trees can be identified by the patchy white on the trees’ trunks, which interestingly enough is caused by a surface fungus that doesn’t affect the tree itself, but the bark.
Not all trees have interesting bark. There may be some in a plant family, such as paperbark maple (Ace griseum), while most of the others are rather nondescript.
Historically, the true non-plastic corks from your wine bottles comes from the bark of a particular oak, which unfortunately doesn’t grow in Illinois.
So, what’s the big deal about bark?
It’s often overlooked as one of the aesthetic qualities of the tree or shrub.
Redtwig dogwood (Cornus) wouldn’t be a worthwhile landscape plant without the red bark during the winter. Burning bush (Euonymus), a potentially-somewhat-maybe invasive plant has corky wings on the bark, which is something that occasionally shows up on sweetgum (Liquidambar) as well.
No one really cares much about the bark during the spring, summer and fall when the tree or shrub is clothed with flowers and foliage. However, come winter when the leaves drop, you’re left with a need for interest.
That’s where attractive or unusual bark becomes a key factor in plant selection for that winter enjoyment.
David Robson is an Extension Educator, Horticulture, at the Springfield Extension Center, University of Illinois Extension, P.O. Box 8199, Springfield, IL 62791. Telephone: 217-782-6515.
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