Ash trees

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.

A large Ash tree stands 30m tall.

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).

An Ash leaf.

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.

Ash seeds hanging from a tree.

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).

The bark of a young Ash tree is pictured on the left and the bark from a mature Ash tree is pictured on the right.

Figure 4: Young ash bark (left); mature ash bark (right)

Similar species

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.