Common Tree Species of the Northwest Forest






Terminology | Pictorial

Fraxinus nigra
Black Ash
Oleaceae (Olive Family)

The black ash is a slow-growing tree of swampy boreal woodlands. Other common names are swamp ash, basket ash, brown ash, hoop ash, and water ash.


General - broadleaved hardwood. Commonly, the largest trees reach a height of 18 to 21 m (60 to 70 ft). Crown is small and open, with large spreding or ascending branches. Branchlets stout; dark buds; trunk light grey bark, soft with corky edges.

Black Ash Leaves - opposite; compond with 7-11 leaflets - oval to lance-shaped, blunt at the base, finely toothed, tapered to a long slender tip; clusters of rusty hairs apparent where leaflets join main leafstalk.

Flowers - polygamous; its flowers are small and inconspicuous. They appear in May or June at about the same time as, or just before, the leaves.

Fruit - The fruit is an elongated, winged, single-seeded samara that is borne in terminal or axillary clusters. It ripens from June to September


Throughout Northwestern Ontario but most common in the southwestern districts. Black ash typically grows in bogs, along streams, or in poorly drained areas that often are seasonally flooded. It is most common on peat and muck soils but also grows on fine sands underlain by sandy till or on sands and loams. Although this species can tolerate semistagnant conditions, for best growth it is important that the water be moving so the soil will be aerated even though saturated.


Black ash wood, easily split, has been much used for baskets. The seeds are an important food to game birds, songbirds, and small animals, and the twigs and leaves provide browse for deer and moose.

More Information - Commercial Profiles for Northwestern Ontario Tree Species.

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