and Deciduous Forest Trees

of Southern Ontario

White Ash
Fraxinus Americana

Location in Ontario:
White Ash grows throughout the Deciduous Forest Region and northward. It is the largest and most common of the Ash trees in Canada.

Ash leaves, University of Guelph Arboretum 
Genus Fraxinus: Ash trees have opposite compound leaves with 5-11 leaflets. Ash can be monoecious or  dioecious depending on the species. Seeds are contained in a single winged samara (a seed in a papery tissue). Ash wood is valued for its strength and hardness. Black, Red and White Ash grow in Ontario, as well as two Carolinian species, Pumpkin Ash and Blue Ash.

TREE FACT: Ash and Hickory are similar, both with compound leaves. Ash leaves are opposite while Hickory leaves are alternate.
Emerald Ash Borer is an invasive beetle accidently brought to North America from Asia in shipping boxes in 2002. It has quickly spread killing millions of Ash trees. Blue Ash has shown some immunity. There is a pesticide that can be used to control Emerald Ash Borer, but it is very expensive, and must be administered every two years. Unfortunately, many non-infected Ash trees have been cut down as a preventative measure. This eliminates trees that may have had a natural immunity. For more information and encouraging news about saving Ash trees:
Save the Ash Tree Coalition

The tell-tale tracks of the Emerald Ash Borer

White Ash trees prefer rich, moist soil.

Landscape Use:
White Ash grow relatively fast, with a nice overall shape and beautiful purple-red leaves in the fall. Unfortunately it is risky to plant White Ash due to Emerald Ash Borer.

A row of White Ash at Rock Point Provincial Park. These trees were removed in 2017, victims of the Emerald Ash Borer.

Leaves: White Ash trees have opposite, compound leaves, with 5 to 9 leaflets, but usually 7. The leaf is hairy only along the veins.

??Red Ash or White Ash?? They are hard to tell apart, except in fall when Red Ash has yellow leaves, and White Ash has reddish-purple leaves. White Ash leaves have whitish undersides, and upper branches that are smooth. The leaf scar is "C" shaped. Red Ash  leaves are densely hairy beneath, and have a "D" shaped leaf scar. The upper branches appear rough.

White Ash in fall colours.

TREE FACT: White Ash leaves are light coloured or "whitish" beneath leading to the name White Ash.

FALL COLOUR WATCH: red to purple

Flowers: White Ash are dioecious (male and female flowers on different trees). Ash flowers are small and darkly coloured, and appear in early spring.

White Ash flowers and emerging leaves

Fruit: Seeds (samaras) form in summer, and fall off in autumn. Some seeds persist into winter. Seed Production happens about every 3 years, after reaching an age of about 20 years.

Samaras of White Ash

Bark: The bark is light gray with intersecting ridges in a strong diamond pattern.

White Ash bark with its distinctive diamond pattern

Size: White Ash is a medium sized tree, growing up to 25 metres, and living to 200 years.

Wood: Ash wood is hard and heavy. It is used for flooring and furniture, as well as hockey sticks, tennis rackets and tool handles.
Specific Gravity:
Janka Hardness: 1320 lb
Wood Comparison Chart

Genetics: White Ash occurs as diploid (46 chromosomes), tetraploid (92 chromosomes) or hexaploid (138 chromosomes). Interestingly, the occurrence appears to be related to latitude: tetraploids occur mostly south of 35 degrees and hexaploids occur mostly between 35 and 40 degrees. Diploids occur throughout the range. Differences in ploidy appear as variations in leaves.

TREE FACT: There is some evidence that Pumpkin Ash, a hexaploid, resulted from a cross between a diploid Red Ash and a tetraploid White Ash.

Beautiful large double White Ash, Norfolk County