When you look at the big picture of the seasons we go through in a year, it comes to our attention that the trees and bushes only have leaves for five to six months out of the year. We grow them for their beautiful leaves, their dense shade for those hot days, their stunning blooms during the spring months, and their brilliant fall colors when autumn arrives. The rest of the time, they lie dormant, leafless and stark.
It is during these six to seven months that we realize these plant materials have a character all their own during dormancy. It is the time of year where we notice different unique characteristics that may not have been as prominent during the growing years. One of these great characteristics happens to be in the form of bark.
We don’t think about it very often, but the bark holds a very important function to trees and shrubs. Not only does it have a function, but its growth character is very different from one species to another, which becomes the overwhelming feature we notice during dormancy.
Bark is tender and smooth when the tree or bush is young and vigorously in its growth stages. It protects the living tissue that creates growth. With time, this outer layer of cells becomes dead and become thicker and thicker with time. This barrier between the outside world and the living tissues inside prevents decay from forming, insects from entering, and disease from causing harm. This is a thick, waterproof barrier that can act as an insulator during cold and hot weather and keeps the main trunk and branches from losing precious moisture.
Most young trees produce a smooth and tender bark for the first few years. With time, the interior of the tree begins to grow and split the outer smooth bark, which in essence creates this cracking, rugged look with time. With winds that bend these trees, this process is enhanced a bit by this subtle splitting. It is a natural process that seems to happen before your eyes.
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Since the dormancy season is long in our region, planting the right species in our landscapes can diversify the character in our gardens. Select a few items that have interesting bark characteristics and color to make the scene a little more dynamic.
People tend to plant many types of birch species and the main attraction is their white bark that periodically peels from the tree in sheets. As long as the tree remains healthy and vigorous, few problems will attack it but put it into stress and you will invite the damaging European birch borer to take control. River birch is another wonderful species that is more tolerant of the borer and has a tan- to coppery-colored bark, which peels off in a more fine character. When older, the trunk almost looks shaggy in appearance.
The Amur chokecherry is a medium-sized ornamental tree that has a shiny copper-colored bark that has a slight peeling character to it. It blooms clusters of white flowers in the spring and maintains the great bark color throughout the year.
Larger trees, such as the American elm, oak, ash and cottonwood, have various elements of deep, grooved bark that can become 2 to 4 inches thick in time. Of course, these tree types can become quite lofty but the large character of the bark looks proportionate. Hackberry produces an interesting bumpy, gray bark that almost resembles small warts. It never quite develops a rigid product. Silver maple will create large, scaly pieces of gray-colored bark that seems to shed layers as it ages.
Species such as the willow varieties develop a very twisted element to the bark. Of the larger species, there is the yellow, black and river willow. There are also smaller, shrubby varieties available such as the Arctic willow. Even though many people feel that this tree is very messy; don’t let it fool you, as it is also one of the most resilient species around. It can weather a storm and repair itself when others would succumb to death. I have even seen very old ones that have blown over horizontally on the ground and continue to grow years and years after as if nothing happened. The weeping willow is very alluring, not only for its bark but also for its graceful weeping habit.
Evergreens also have interesting bark to view. Usually, it is of a scaly nature and sometimes has a copper resin that bleeds from it. This resin shines in the winter sun for a completely different element. Some pines have a nice copper or reddish color to the bark such as the Red or Scotch pines.
Shrubs can have good winter character also, such as the red and yellow-twigged dogwoods. Their colors are quite vibrant against the white of the snow during winter. The Flame willow has a light orange coloring to its bark that seems to burst into heat during the month of March when this color turns a deep glowing orange hue. If you drive by a hedge of these, you cannot mistake it for any other. Many species of the ninebarks have a light-colored, papery bark that tends to peel with age also.
This is a great time of year to notice some of these bark characteristics and plan for a little diversification in your landscape for the years to come. Take a camera with you and shoot some of the ones that catch your eye so when planting time arrives in spring, you will know exactly what you want.
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The character of bark on our trees and shrubs can be a quiet element during the growing season, but it sure can make a loud statement during the months of dormancy. Winter doesn’t have to be a drab season if you make sure to diversify your plant products in the landscape that have many different characteristics.
