Sweetgum is a distinctive tree at any time of year. It stands out among most other deciduous trees with its excurrent growth habit, which gives it a narrowly conical or pyramidal shape. Only in its advanced age does it begin to develop a more rounded and irregular form. Its leaves are star-shaped with either five or seven lobes and span between four and seven inches. Their glossy green color gives way to a wide range of colors in the fall, including yellow, orange, red, and maroon, remaining on the tree for several weeks depending on weather conditions. The fruits are particularly distinct, especially in the winter after the leaves have dropped. Woody balls made up of a series of capsules with pointed beaks hang from long stalks throughout the winter, windborne seeds having been released from small openings in the fall. Without even bothering to look at the twigs, seeing these durable, spiky balls hanging from branches (or feeling them under your feet) is a quick indication that you are looking at a sweetgum.
Liquidamabar styraciflua (one of the funnest botanical names to say) was previously placed in the family Hamamelidaceae but is now one of the few members of Altingiaceae. Its natural distribution is broad, covering a large portion of the eastern United States and west into Missouri then down into Texas, Mexico, and much of Central America. Outside of its natural range it has been widely planted as an ornamental, and there are several popular sweetgum cultivars currently in cultivation. Both the common and botanical names for this tree refer to the resin found in its bark, which historically has had many uses.
The winter twigs of sweetgum are stout, round, smooth, and yellow-brown to green or olive-green to brown-purple in color. They can also be glossy and feature a few scattered lenticels. Older twigs (or branchlets) are brown at first and then light grey with dark grey lenticels. They are occasionally adorned with corky wings similar to those of bur oak. Because the wings aren’t always present, it can be a fun thing to encounter when you are out looking at twigs.
The winter buds of sweetgum twigs are egg-shaped and made up of bud scales with acute tips and ciliate margins. They are green to orange-brown or reddish in color and occasionally sticky. Lateral buds are alternately arranged, are much smaller than terminal buds, and are stalkless and flattened against the twig. They sit above a slightly raised leaf scar that is half-elliptical to triangular in shape and has three distinct vascular bundle traces. The pith of sweetgum twigs is solid, continuous, brownish, and irregularly shaped.
Sweetgum bark is light to dark grey and is made up of a series of rough, vertically arranged, scaly ridges that become deeply furrowed with age. The mace-like fruits of sweetgum are about one inch wide and, at a glance, are similar in appearance to the seed balls of sycamore trees; however, sycamore seed balls easily break apart when compressed, while the pointed, woody capsules that make up a sweetgum ball are held firmly together and can hold their shape for long periods of time. When these “gumballs” collect on the ground below, they can become a hazard, especially where there is lots of foot traffic. Speaking from experience, they are also obnoxious when operating a mower. This polarizing feature has resulted in bad opinions of the sweetgum tree. Luckily, some people are out there defending it.
awkward botany 