By Jon Morgenson, Park Horticulturist
We get a lot of questions in our Landscape Services program from people asking “What tree can I plant that will have good fall color?,” and by that they mean oranges, reds and even some purple not just yellow or gold or yikes only a faded green or brown. An answer not as frequently given as selections of maples or oaks is Sweetgum.
American Sweetgum (Liquidambar styraciflua) has been considered to be a tree for more southern or at least warmer climates than Nebraska’s even though it is native to cold areas of the country and is found commonly enough in Lincoln where I work and has proved to be pretty darn tough. There are several Sweetgums doing well at the Lincoln NGPC office grounds and other trees close by on the East Campus of UNL. Also I have grown Sweetgum from seed collected in Lincoln and those trees did very well.
Sweetgum is medium to fast growing tree that reaches 50-70 feet tall in the landscape and taller in the wild. It is native from southern Connecticut south to Florida and west through southern Ohio, Indiana, Illinois, Missouri, and parts of Oklahoma, Texas and Mexico. Under natural conditions Sweetgum is found growing in slightly acidic rich moist woodlands soils, and in alluvial soils along stream and river courses. It is considered a pioneer species in its native haunts and spreads into open areas especially in moist sandy and loamy soils. Being a pioneer species may help explain why it has the ability to do well outside of its native range and in differing soils. Soils that are extremely dry and alkaline pose a problem for Sweetgum as they do for many moisture loving lowland tree species such as Pin Oak; foliar chlorosis can be a common problem. Having said that, I will repeat there are many nice Sweetgums in the Lincoln area and once established (more on this later) Sweetgum does quite well in our eastern Nebraska climate.
The foliage of American Sweetgum is a 4-7 inch simple leaf similar in shape to a flat bottomed star with 5-7 pointed lobes. The summer color of the leaf is dark glossy green changing to hues of red, orange, yellow and even purple in the fall. Fall coloration can vary from tree to tree especially with seed grown trees and would be more reliable with the purchase of a named selection. The stems that bear these star shaped leaves are a golden-brown to reddish color and can develop a corky winged bark similar to Burning Bush (Euonymus alatus); some plants develop very corky stems and have been selected for this interesting trait. The trunk is straight and brownish –gray in color and has bark that becomes deeply furrowed. The outline of Sweetgum is pyramidal in youth becoming more rounded with age. The fruit according to Dr. Michael Dirr in his ‘Manual of Woody Landscape Plants’ is a “syncarp of dehiscent capsules”. Let’s just say it is a woody, cone-like fruit similar in shape to a miniature medieval knight’s mace. The fruits do pose a problem for ‘neat freaks’ as they persist and can cover the ground beneath a mature tree; they are used in crafts and the seeds are eaten by song birds and small mammals. A resin-like gummy sap was once collected from beneath the bark of the tree and chewed hence the name Sweetgum. The wood of Sweetgum is used for paper, plywood and quality lumber.
If choosing Sweetgum for a landscape tree select a sunny, moist site that does not have a high pH (alkaline) soil and consider if the woody fruits will cause a problem in surrounding turf areas. Sweetgum has a fleshy coarse root system and is best transplanted in the spring and needs to be watered regularly for several growing seasons to give it a good start and a generous circle of mulch such as wood chips (3-4 inches deep) added after planting would be great to help retain moisture.