Last updated November 18, 2021. All photos by the author.
A small sweetgum tree at an urban park. This tree’s leaves turn many colours in the fall making it a spectacular find.
Like the London plane tree, I came to identify this species by wondering, “Why doesn’t that maple tree have maple seeds?” Liquidambar styraciflua is native to the southestern United States but is planted here in parks and parking lots. It is easy to identify year-round because of its characteristic 5-lobed leaves and spiky “gumballs” that persist through all seasons. The wild trees typically grow to 20 metres tall (65 feet) and have pyramidal crowns up to 18 metres wide (60 feet).
Leaves typically have 5 pointy lobes. These ones are starting to change colour in mid-October. Although “maple-ish” in appearance, these leaves attach alternately to the tree (maple leaves are oppositely attached.)
Fallen sweetgum leaves in mid-October. It’s easy to see the palmate venation on the left.
Looking up from close to a sweetgum trunk. Many branches stretch out from the trunk.
Sweetgum branches against a cloudy sky in early November. Although this tree has lost almost all its leaves, it is still easy to identify because the “gumballs” stay on the tree year-round. There is a gumball-free cultivar for areas where falling gumballs would be too much of a nuisance to balance the benefit of beautiful fall foliage.
This year’s gumballs. Once dry, they turn black and release seeds that are enjoyed by birds and small mammals. Notice how some balls are hanging singly and others in clusters.
Dry gumballs. The spiky cases hide seeds that can be eaten by birds and small mammals like squirrels. Some gumballs hang alone, but I’ve noticed most are in clusters like these ones.
Dry gumballs hanging on a tree in fall. Look at the myriad colours that these leaves turn!
The ground beneath a sweetgum tree in early November. This particular tree had leaves with 5, 6, or 7 lobes.
A sweetgum tree in early November. One tree had leaves that were green, yellow, orange, red, and purple.
This sweetgum tree in early November had so many colours of leaves, but what was most interesting to me was that the leaves had 5, 6, or 7 lobes. Previously I had only seen 5-lobed leaves.
Sweetgum bark. This tree is not very old and does not have the characteristic deep ridges yet. Look for light grey bark on both young and mature trees.
The base of the same tree. The furrows/ridges are more noticeable lower on the tree.
Close up of sweetgum bark. This young tree has bark with a texture in between the smoothness of a sapling and the deep vertical ridges of a mature tree. This tree was host to several types of lichen.
Close-up of a mature sweetgum tree’s bark. Vertical furrows are covered with moss and lichen.
Sweetgum got its common name from its sap, which can be dried then chewed like gum. Other names include American sweetgum, alligatorwood (because of the bark’s resemblance to that reptile’s skin), American storax, hazel pine, bilsted, redgum, satin-walnut, and star-leaved gum. Here’s an excerpt from a paper about this tree:
Sweetgum trees are large, deciduous trees found in Asia and North America. Sweetgum trees are important resources for medicinal and other beneficial compounds. Many of the medicinal properties of sweetgum are derived from the resinous sap that exudes when the outer bark of the tree has been damaged. The sap, known as storax, has been used for centuries to treat common ailments such as skin problems, coughs, and ulcers. More recently, storax has proven to be a strong antimicrobial agent even against multidrug resistant bacteria such as methicillin-resistant Staphylococcus aureus. In addition to the sap, the leaves, bark, and seeds of sweetgum also possess beneficial compounds
So go outside this week, or any week, and find a tree with spiky balls and grey, grooved bark. If you are lucky, there will still be a few colourful star-shaped leaves around it for you to enjoy.
