Not everyone is sweet on Sweetgum trees
Gumballs! How many of you have cursed those little spiky spheres that fall from trees and cause you to twist your ankle — almost?
Well, those trees are natives here in central Virginia, and they have some really good qualities.
I just read a book by Doug Tallamy extolling the virtues of oaks, and I admit sweetgums may fall a little short of oak trees in value. Nonetheless, while perhaps not book-worthy, they are certainly article-worthy.
Underutilized in the landscape
Native to the South, sweetgum is found naturally in moist areas. It is a nice ornamental tree with a conical form and lovely foliage. It grows rapidly and prefers a sunny location with slightly acidic, well-drained soil.
Relatively pest-resistant and disease-free, it works well in urban and suburban settings, reaching 30 to 60 feet. Since sweetgum trees can live up to 400 years, your home landscape requires space for a mature tree.
The tree is also called gum tree, hazel pine, incense tree, alligator wood and redgum. Its botanical name, Liquidambar styraciflua, refers to its viscous resin, literally “liquid amber flowing with gum.” When the outer bark is damaged, the resinous sap or storax flows.
Medicinal uses past and present
The resin’s antiseptic and antibacterial qualities were known to the indigenous North and South American peoples. Sweetgum sap was used for medicinal purposes: by mouth to treat diarrhea, topically as a salve for wounds, and as a tea to calm nervousness.
Appalachian settlers made a concoction of resin and whiskey to clean teeth, heal gums and mouth lesions, and relieve toothache.
As an expectorant, boiled and cooled sap was used to treat fevers, bronchial infections and croup. In the past, balls of sap were even placed in dogs’ noses to treat distemper.
In a 2014 study by Jody Lingbeck et al., published in the Pharmacognosy Review, storax has been proven to have antimicrobial properties against drug-resistant bacteria including Staphylococcus aureus.
Studies show that extracts from the sap suppress hypertension in mice, have antifungal properties, and may have use as organic pesticides.
The leaves, bark, and seeds of sweetgum contain beneficial compounds such as shikimic acid, from which the active ingredient in the antiviral Tamiflu® is derived.
Marketed as “satin walnut,” sweetgum wood is medium in density and strength. In Southern hardwood forests, it is second in production to oaks.
While its sapwood is creamy, the heartwood is pink to reddish brown so they are often marketed separately. Since the wood can warp easily, it is usually laminated onto a stronger wood or used in veneers.
Crates and plywood are also made from sweetgum lumber.
While there are commercial and medicinal uses for sweetgum trees, what are the reasons to grow them in your yard?
The first is for their star-shaped foliage. In the spring and summer, leaves are shiny green from above and fragrant when crushed.
But they really put on a show in autumn. Typically, the leaves turn color early and trees hold their colorful leaves for a long time. On one tree, you might find maroon, bright red, pink, orange, gold and yellow leaves.
Prized value to wildlife
Another reason is for the value it provides to wildlife. Sweetgum is the larval host for over 30 butterflies and moths, including the large green Luna moth. In the spring, hummingbirds stop at its insignificant greenish blossoms on their way north.
Songbirds, including American goldfinches, as well as waterfowl love the seeds gumballs drop each fall. Gray squirrels, chipmunks and rabbits also feast on the seeds.
What to do with gumballs
In Dirr’s Hardy Trees and Shrubs, the sweetgum is described as a “lovely tree [that] would be on every gardener’s wish list were it not for the woody, spiny, capsular, 1 to 1½ inch diameter fruit.” These prickly orbs are called gumballs, goblin balls and monkey balls (or more colorful names when stepped on).
If you look at a gumball closely, you will find dozens of fruits fused together with the spikes or beaks arranged in pairs. As the balls dry, they turn from green to brown.
During the drying process, holes appear. Each hole contains two tiny winged seeds. Each gumball produces 30 to 50 seeds, which are typically dispersed by the wind. Any precious unwinged seeds provide food for wildlife.
If you’re handy with a glue gun, you can craft gumballs into garlands, tabletop Christmas trees or wreaths. Colonial Williamsburg even showcased gumballs in a welcoming pineapple-shaped front door decoration.
Not crafty? Gumballs can be used as free mulch to reduce weeds and retain moisture. The spiny surface keeps slugs at bay. Although they’re not good fire-starters, they burn well in an existing hot flame.
If you want the tree but not the mess, you can purchase a roller tool to sweep up gumballs. Or choose cultivar ‘Slender Silhouette’ — a 2011 Gold Medal Award recipient from the Pennsylvania Horticultural Society — which, due to its narrow form, produces few fruits and drops them in a small space.
Alternatively, you could plant a sterile cultivar such as ‘Rotundiloba’ that doesn’t produce gumballs at all — sweet!
Lela Martin is a Master Gardener with the Chesterfield County office of the Virginia Cooperative Extension.