The leaves of Fraxinus quadrangulata are compound and opposite. It can usually be distinguished from the other three species of ash in Wisconsin by the presence of 4-angled or 4-winged branches (in slow growing trees this character may be poorly expressed). The fruits are broad with strongly flattened seeds.

The main distribution of Fraxinus quadrangulata is from Missouri to Tennessee and north to Ohio and Illinois. There are scattered, disjunct populations in the surrounding states, including Wisconsin where it is known from only a few sites in Waukesha County.