Boxelder, Dogwood and Maple trees also have opposite branching. Hickory, Butternut, Oak, Cottonwood and Quaking Aspen trees have alternate branching.
These 5 to 11 leaflets compose a single leaf. A Maple tree is an example of a single leaf tree that has one large leaf extending from the petiole.
Don’t assume a tree without seeds is not an ash tree. Some types of ash are seedless. Seed clusters only form in late fall and early winter. Boxelder seeds are also clustered; however, they look like wings, rather than paddles.