Last week I profiled winterberry holly and its landscape design value. A few other shrubs have special appeal in winter, but river birch (Betula nigra) is a tree that also fits the bill. Its light papery bark develops a pleasing contrast to the other trees and shrubs in the yard.
River birch bark is not as striking from a color standpoint as the white birches that grow up north, but the salmon colored flakiness makes up for it. Pigmentation is somewhat muted as trees age, but larger specimens are eye-catching in and of themselves. Male flowers develop in fall and these worm-like catkins persist on the branches all winter.
Female flowers emerge in spring. They look like little cones. As they develop, the male
river birch male catkins in winter
flowers begin to shed pollen and by fall a healthy population of seeds spreads throughout the landscape. Summer foliage is diamond-shaped and doubly serrated. This means leaf edges have big teeth with smaller ones in between them.
River birch eventually becomes a medium sized tree. I’ve seen some specimens 80 feet tall with a trunk diameter of about three feet, but that’s rare. Typical height is 40-50 feet with a canopy spread of nearly that on a sunny location.
A big advantage of this species over many other shade trees adapted to our area is that they grow in a wide variety of soil moisture and pH ranges. They thrive in wet places better than most landscape trees and once they become established they tolerate drought fairly well.
Iron chlorosis causes leaves to develop green and yellow striping. This deficiency symptom is common on soils with pH values nearing neutral. Iron chlorosis slows growth slightly and is easily controlled by applying iron to the soil or foliage.
River birch is resistant to bronze birch borer and Verticillium vascular wilt. Trees are quite susceptible to spiny hazelnut aphids though. These critters reside on leaf undersides and are readily detected as leaves develop ridges. Infestations usually take place early in the year and generally don’t affect the overall health of the tree.
River birches even have a fringe benefit. As spring approaches they develop sap much like maple trees do. This sap can be consumed directly and it is totally safe to drink without any treatment. Sap can also be boiled down into syrup. The flavor is a little different than maple or sweet birch syrup, but is quite rich and pleasing with a hint of wintergreen.
My only experience making birch syrup was mixed. Sugar content is not as high as sugar maple and the sap is more complex. Many other compounds are present besides sucrose. That gives it the rich taste. However, making the syrup requires more care. It burns more readily, so the heat must be lowered as the syrup nears its readiness.
Several herbal sources tout river birch as a medicinal plant. I have never used it for that purpose, but I’ve also never encountered any side-effects from consuming sap, syrup, or tea made from leaves or inner bark.
Healthy young river birch in winter
flaky river birch bark
Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).
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