White Ash (Fraxinus americana)

[ Trees > Hardwoods > Ashes . . . ]

Forest Types: Oak-Hickory, Beech-Maple, So. Riverine, Appalachian Cove


Bark dark grayish brown, deeply cut into X shapes; leaves compound, with 5-9 candle-flame-shaped leaflets; leaflets with whitish undersides; twigs and samaras distinctive (see below); growing east of the Great Plains.

by Michael Kuo

Habitat: Varied; surviving well in several different forest types; fond of moist soil, but able to survive elsewhere; growing east of the Great Plains.

Stature: 50-80 feet high; to 3 feet in diameter; with an open crown.

Leaves: Compound; composed of 5-9 leaflets arranged more or less in pairs, with a single leaflet at the end; leaflets dark green above and whitish to greenish below, candle-flame-shaped; edges slightly toothed or nearly smooth; stemlets to 1/2 inch long.

Bark: Dark grayish; deeply cut into X shapes (or "diamond" shapes, depending on your perspective).

Fruit: A small samara or "wing" 1-2 inches long; hanging in dense clusters; the hard, seed part not extending far into the flat, wing part (see below).

White ash is nearly identical to green ash, and a suite of subtle characters must be used to separate the two trees. In theory the leaves of white ash have a more whitish underside, but this character is unreliable in my experience. The stature of the two trees is usually (but not always) distinctive; the branches of green ash tend to spread outward somewhat more. The samaras of the two trees are usually different: the hard, seed part extends more into the flat, wing part in green ash than in white ash:

Fraxinus americana and pennsylvanica

. . . but the leaf scars on twigs seem to me to be the most reliable character for comparison. The white ash leaf scar is generally larger, more puckered looking, and more U-shaped:

Fraxinus americana and pennsylvanica

When samaras, twigs, leaves, and stature are considered together it is usually possible to make an identification--but the features do seem to intergrade between the species sometimes, making precise identification difficult. Some authors emphasize the extent of the serrations on the leaflets, but I find this character unreliable.

(References consulted)

Frequently Associated Mushrooms:

Gyrodon merulioides is exclusive to ash. Black morels and yellow morels are frequently found under ash. Perenniporia fraxinophila is an ash-loving parasite that causes severe heart rot.


Fraxinus americana

Fraxinus americana

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Kuo, M. (2010, November). White ash (Fraxinus americana). Retrieved from the MushroomExpert.Com Web site: