White ash

Frêne blanc

Fraxinus americana L.Oleaceae (olive family)

Origin: Eastern North America (native in Ontario)


White ash is a medium-sized tree with a tall straight trunk and a pyramidal crown.

Read more about Tree, Bark, Twigs


Leaves are pinnately compound with 5 to 9, but usually 7, leaflets branched off a central stalk.

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Male and female flowers are tiny, lack petals, and are borne in dense clusters.

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Fruits are pale green or yellowish winged seeds (samaras) hanging in clusters and maturing in the fall.

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White ash is a medium to large tree, up to 30 m (98') and 150 cm (5') in diameter with opposite, upright branches.

Trees have straight trunks with arching branches, that, in open-grown trees form a broad crown.

Bark on young trees is smooth and light grey.

Bark on older trees has deep furrows between narrow intersecting ridges that form a diamond-shaped pattern.

Twigs are grey, shiny, hairless, often with a waxy grey-white coating. Leaf scars are C-shaped.

Buds are reddish brown and round. The terminal bud is 5 - 14 mm (1/8" - 1/2") long, often wider than long, sometimes with a nipple-like tip, and flanked by two smaller lateral buds.

Branches and leaves have an opposite arrangement.

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Leaves are 15 - 25 cm (6" - 10") long, pinnately compound with 5 to 9, but usually 7, leaflets.

Leaflets are 6 - 15 cm (2 3/8" - 6") long, oval, sometimes wider above or below the middle, with abrubtly pointed tips and round or tapered bases. The edges are smooth or with sparse rounded teeth. The underside is pale and hairless.

All but the terminal leaflet have a short stalk 5-10 mm long, that is not winged (or barely so).

In fall leaves turn yellow or a distinctive bronze-purple, and drop their leaflets one at a time.

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Male and female flowers are tiny, lack petals, and are borne in dense clusters on separate trees in May before or as the leaves emerge. Male flowers are purple and yellow.

Female flowers are greenish.

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Fruits are pale green or yellowish winged seeds (samaras) hanging in clusters on female trees and maturing in the fall.

Fruits are 2.5 - 5 cm (1" - 2") long. The wing encloses about 1/3 of the seed.

Fruits may remain on the tree into winter.

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White ash grows from Cape Breton Island as far south as Texas and Florida. It is the most common ash in Canada, although its natural range is smaller than that of red or green ash (Fraxinus pennsylvanica).

Derivation of names

The genus name Fraxinus is the classical name for the ash trees. It is derived from the Greek word phraxix, meaning separation, which is in reference to the European use of ash trees as hedges. The species name, americana, indicates that the species is from America.

Human use

The wood of white ash has great commercial importance. It is used to make baseball bats, hockey sticks, and tennis rackets, as well as barrels, ladders, boats, and furniture.

Aboriginal peoples also had many uses for white ash. Some used the bark to produce a yellow dye, while others believed the leaves prevented snake bites and carried them when walking through snake-infested woods. The leaves were also used in a poultice to treat snakebites and the juice from the leaves and inner bark has been used to treat mosquito bites.

The threat of the emerald ash borer

White ash, along with other native and introduced ash species, is currently threatened by the emerald ash borer (Agrilus lanipennis). This insect pest, brought from Asia, was first detected in the US and Canada, including the GTA, in 2002, and has already killed millions of ash trees. Ash mortality from this pest is expected to be on the scale of the decimation of North American elms from dutch elm disease and American chestnuts from chestnut blight in the 20th century. Removing and replacing dead ash trees will cost municipalities, homeowners, and businesses millions of dollars over the long term.

Because of the threat posed by emerald ash borer, no ash trees of any kind should be planted until effective control and eradication measures are developed. Since the movement of ash wood products like mulch, firewood and logs significantly contributes to the spread of emerald ash borer, these products should not be transported from place to place.

For additional information including symptoms of infection, treatment and implications see: Natural Resources Canada factsheet and City of Toronto factsheet.

Wildlife value

The seeds of white ash provide food for ducks, grouse, wild turkeys, and various species of songbird.

Related species

Some species of ash trees are difficult to tell apart. White ash may be confused with green ash, which is also planted in urban areas as a cultivated tree. The best characters to look at to tell these species apart are the bark, the terminal buds and leaf scars on winter twigs, leaflet stalks, and fall colour.

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White ash IN TORONTO

White ash's place in Toronto's urban forest

White ash has been widely planted in Toronto's parks and it provides unique and attractive fall colours when its leaves turn a distinctive bronze-purple and its light patterned bark adds to the display. The future of ash trees in Toronto is now uncertain because of the accidental introduction of the emerald ash borer (see above in Fascinating Facts). The City has begun a program of vaccinating thousands of trees on public land.

Landscape value and potential for home planting

Because of the presence of emerald ash borer in our region (see above in Fascinating Facts), no species of ash should be planted at this time.

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WHERE CAN I SEE White ash?

Find trees on Tree Tour maps at Canadian Tree Tours:

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