Trees of Wisconsin

Fraxinus pennsylvanica Marshall
green ash; red ash
Family: Oleaceae
tree leaf bark twig flowers fruit
Fraxinus pennsylvanica has opposite, compound leaves with short-stalked leaflets that are not strongly whitened beneath. The upper edge of the leaf scar is not strongly concave as in F. americana, and the first pair of lateral buds are generally not separated from the terminal bud as in F. nigra. The above not withstanding, F.pennsylvanica is extremely variable and caution is recommended in identification, because it is frequently misidentified as either F. nigra or F. americana. The twigs range from glabrous to densely pubescent (the primary character used to split this species into varieties when Red and Green Ash are distinguished), the shape of leaves and leaf scars is variable, and it is not uncommon for some lateral buds to be sub-opposite rather than clearly opposite. The youngest leaves of seedlings may be simple rather than compound. The flower buds are highly prone to deformation, sometimes confusing observers. See paragraph 2 of the discussion of F. americana for a comparison of characters among the Ash species.

Fraxinus pennsylvanica is by far the commonest ash species in southern Wisconsin. It is present in many of the disturbed wet forests and is also a very aggressive invader of old fields and other disturbed, open sites. See the discussion of Black Ash.

Comparison of leaves and twigs of Fraxinus americana, F. nigra and F. pennsylvanica.

Comparison of fruits for Fraxinus americana, F. nigra and F. pennsylvanica.

known Wisconsin distribution


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