The Nature of Eureka: Sweetgum the Star of Fall

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Fresh beaver activities marked a trail for a fall hike. A small dam under construction made hiking difficult in the water-soaked thicket. Fortunately, the beaver left a collection of neatly carved “walking sticks” along the creek’s edge. Nearby stood a stand of old sweetgums girdled by a beaver. The source of the generic name for the tree, Liquidambar, was in strong evidence. At the top of the girdled scars were oozing drops of “liquid amber,” moving like glaciers from the tree’s veins. It is this gum resin that provides the tree’s product of commerce.

The liquid is the consistency of honey when fresh, but hardens to a soft amber-like substance upon exposure to air. It has an aromatic, balsam fragrance, and a mild, pleasant flavor, slightly bitter and warm. The color is more or less transparent yellow, becoming cloudy and darker upon aging. It makes a good chewing gum, known to any school boy a hundred years ago throughout the tree’s range.

American Sweet Gum, Liquidambar styraciflua, grows from Connecticut, west to Arkansas and beyond, then south to Guatemala and Honduras. The gum, used in the antiseptic tincture benzoin, is primarily harvested in Central America, where the hot tropical sun seems to produce more gum resin beneath the bark. The trees are tapped to collect the gum resin in buckets.

The leaves are nearly star-shaped and have five to seven deep, sharply-pointed lobes, similar to maple leaves. The prominent lower veins exude a sweet fragrance when bruised or broken. In autumn they turn a deep crimson red, yellow or dull purple colors.

The leaves also contain an essential oil that contains the same antiseptic components as Australian tea tree oil, available wherever essential oils are sold and touted as a natural antiseptic. In 2010 a research group at the University of Arkansas found that sweetgum contains significant quantities of shikimic acid, a medicinal compound used as the starting material for the manufacture of the prescription flu drug, Tamiflu. Star Anise from Asia is the current source of shikimic acid, and there are reported shortages.

Speaking of shortages, given our dry warm fall, we will probably have shortages of colorful fall foliage. You will be able to pick out the sweetgum trees in Eureka Springs, as they will have some of the showiest color amidst the drought.

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