Ash Tree Identification
(F1633, Reviewed Jan. 2024)Ash trees (in the genus Fraxinus) are susceptible to attack by the emerald ash borer (EAB), a non-native insect. The first step in determining if a tree has been infested with EAB is to make certain that it is an ash tree.
Ash Tree Identification
Branch and Bud Arrangement
Buds and branches normally are found directly across from each other and not alternating along the stem. Note, however, that buds and branches may die; therefore, not every branch will have an opposite counterpart.
Leaves
Ash trees have compound leaves, composed of five to 11 leaflets. Leaflet margins are serrated and leaflets are opposite each other, except for the single leaflet at the tip. The only other tree species with opposite branching and compound leaves are boxelder (Acer negundo) and Amur corktree (Phellodendron amurense).
Trees that Resemble Ash
Boxelder (Acer negundo)
Boxelder has opposite branching and compound leaves, but the leaves have only three to five leaflets. In seed clusters, seeds always occur in pairs instead of singly. The twigs of boxelder trees often are blue/purple with a white, waxy covering.
Black walnut (Juglans nigra)
The compound leaves of black walnut contain nine to 15 leaflets, but the leaves occur in alternate placement on the branches. Fruits are large nuts contained in green husks that turn black in late fall.
Amur corktree (Phellodendron amurense)
This tree rarely is planted in North Dakota; it’s found only in a few landscapes. Like ash, corktree has compound leaves that are arranged opposite on the twigs. However, corktree leaves may contain as many as 13 leaflets. Leaflets are shiny and the fruit is distinctly different from ash.
