Ash trees are commonly found in streets, parks, and forests throughout Ottawa and the rest of Ontario. (Figure 1). There are three species in Eastern Ontario: white, green, red and black ash.
Figure 1: Ash are typically large trees reaching up to 30m tall at maturity
Branches and leaves
Branches and leaves grow in an opposite pattern. Where one leaf or branch emerges, another grows directly opposite. .
Leaves are typically 5 to 15 cm long and compound with 5 to 11 leaflets (Figure 2). Leaflets have either smooth or toothed margins (edges).
Figure 2: Green ash leaf
Ash seeds hang in clusters of single, oar-shaped seeds and are often shrivelled (Figure 3). Clusters typically stay on the tree until late fall or early winter.
Figure 3: Hanging clusters of ash seeds
Trunk and Bark
Young trees have smooth, light grey bark. Older trees have furrowed bark with a diamond shaped ridge pattern (Figure 4).
Figure 4: Young ash bark (left); mature ash bark (right)
Several common landscape trees may be easily confused with ash. Manitoba maple is the only other tree species with compound leaves and an opposite branch and leaf arrangement. Manitoba maple has distinctly lobed leaflets. Black walnut, Butternut and Hickory have similar leaves to ash, however, they have an alternate leaf arrangement.