: Liquidambar styraciflua
Our yard has two large sweetgums, and several young ones growing in the scrub; one has shot up from the exposed root of an older tree. Gum trees used to be a favorite hiding spot for my special toy koala, due to a linguistic serendipity by which they share the same common name as the Australian eucalyptus trees he was always homesick for.
North American sweetgum trees are not at all related to the other sort of gum tree, of course. They are in the same family (Hamamelidaceae) as witch hazel, flowering deciduous trees with related species in Asia and South America. The common name comes from the resinous sap, which was apparently instrumental in the invention of polystyrene, and has been used as a cheap substitute for everything resin has ever been used in, from perfume to waterproofing. Presumably, this sap is also the source of the barely-Latinate genus name Liquidambar. Also, the sweet taste led to the gummy sap being used as chewing gum in early America, although I know of no modern food products which use it. I've also never seen a sweetgum bleed, being toward the northern edge of its range, but handling the fallen gumballs in large numbers will make your hands sticky, and leave them smelling resinous and slightly sweet.
The gumballs are the fruit of the sweetgum tree, green when still on the tree and turning pine-needle-orange before they fall in the autumn. They are spike-covered spheres a bit more than an inch in diameter, and are largely indestructible, usually visible in the litter below the tree year-round, though the older ones will be gray and have lost most of their spikes. They're prickly, numerous, annoying, and good for absolutely nothing, unless you want to set a trap so that people walking in your yard will trip and break their ankles - gumballs are very good for that. They're also occasionally put to use by desperate crafters - Halloween spiders and Christmas tree ornaments are what I've seen most often - but long-term, they're far from durable, and I don't recommend them in anything meant to last. Up close, though, they have an elegant mathematical beauty, and in their pointed spherical symmetry, they look as if they belong in the world under a microscope.
Sweetgum flowers are also round, small green puffballs on droopy stems. The male flowers fall to the ground as clusters about the size and color of peas, organized in small bunches like grapes, looking like miniature pom-poms. They crumble into tiny grains when touched. As a child I used to mush large numbers of them into water to make "pea soup" for my dolls.
The leaves are distinctively star-shaped, with five or occasionally seven well-formed points, and grow alternately, which is apparently an important way to distinguish them from maples, as the points are sometimes more ambiguous. The leaves turn bright yellow to deep burgundy red in autumn, and tend to drop early and quickly without drying out, leaving gumballs still visible all over the bare branches.
Sweetgum wood wasn't often used for lumber until the early 20th century, but with changes in the lumber industry it's now the country's top source of plywood, and the tightly-grained reddish wood is also sold as a hardwood, usually under more elegant names. Sweetgum is a very common tree all over the southeastern US, from Pennsylvania to eastern Texas, especially on roadsides and streambanks. In the Middle Atlantic and Southeast regions it is an important component of the oak-gum and oak-gum-cypress forest communities that cover large areas of land. It grows to 100 feet high, with a spreading crown, and is often planted around the country as a fast-growing shade tree, though I question whether it's worth having the gumballs all over the garden!