Medicinal, Environmental, and Other Products From Tree Bark

Native Americans

I admire the resourcefulness of the Native Americans.   They lived off the land without any of the comforts that we enjoy today.  There was no electricity, running water, or cell phones.  At times the cell phone is not very high on my list of comforts.   Medicine at the time was largely developed by trial and error from local trees and plants.  Numerous health and environmental products have been developed over the years from tree bark.

Bark Basics

Bark is the outermost layer of a woody stem. It serves as protection against damage from parasites, herbivorous animals and diseases, as well as dehydration and fire. Bark can also contain antiseptics like tannins, that protect against fungal and bacterial attacks that would cause decay.

Medicinal Uses

Dental hygiene was likely not a critical issue at the time, but dental pain was extremely important.  As necessity is the mother of all invention, they discovered that the bark of the willow tree (Salix sp.) was soothing for tooth and gum pain.   Willow bark contains salicylic acid which is now used as the active ingredient in aspirin.

Slippery elm is a common tree species in the US South with limited commercial value.  The inner bark is the source for slippery elm lozenges.   An interesting anecdote about these lozenges is that they were once the source of the extra mucus needed by professional baseball pitches to throw a spitball, which was a legal pitch during the turn of the last century.  The lozenges are still popular for sore throats across North America.

The bark of the cinnamon tree is used as a spice and has medical properties.  Industrial oils are distilled from its bark and leaves in Southeast Asia. 

Cinchona alkaloids from the bark of Cinchona sp. Product quinine for the treatment of malaria and quinidine for the treatment of heart arrhythmia in Latin America.

Other Uses

Toxic heavy-metal ions, especially lead, cadmium, and zinc, from industrial waste waters can be adequately absorbed by the bark of several tree species.  Bark can be used as a substitute for expensive synthetic ion-exchange resins in North America.

In the cork oak (Quercus suber) the bark is thick enough to be harvested as a cork product without killing the tree; in this species the bark may get very thick (e.g. more than 20 cm). Some barks can be removed in long sheets; the smooth surfaced bark of birch trees has been used as a covering in the making of canoes, as the drainage layer in roofs, for shoes, backpacks etc. The most famous example of using birch bark for canoes is the birch canoes of North America.

The inner bark (phloem) of some trees is edible; in Scandinavia, bark bread is made from rye to which the toasted and ground innermost layer of bark of scots pine or birch is added. The Sami people of far northern Europe used large sheets of Pinus sylvestris bark that were removed in the spring, prepared and stored for use as a staple food resource and the inner bark was eaten fresh, dried or roasted. 

Cork oaks are harvested every nine years, once they reach maturity. It doesn’t harm the tree, and the corkbark regrows. I have personally seen this operation in both Portugal and Spain. The year of harvest is marked on the trunk, so each tree isn’t harvested at the wrong time.  So, if you have ever removed a cork from a wine bottle, you have enjoyed the benefits of bark.

Meet the Author

Dr. Todd Shupe is the President of Wood Science Consulting, LLC. He is a well-recognized expert on wood forensics, wood preservation, wood decay and degradation, and wood species identification. He has a broad background in new product development, quality management, and marketing and sales in both the public and private sectors. For more information please visit DrToddShupe.com.

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