Fraxinus pennsylvanica (Green Ash)
|Also known as:
|sun; average to moist; forests, floodplains, old fields and field edges
|May - June
|50 to 110 feet
|Wetland Indicator Status:
|GP: FAC MW: FACW NCNE: FACW
|MN county distribution (click map to enlarge):
|National distribution (click map to enlarge):
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Flowers are borne on feathery, 1 to 2-inch panicles, from leaf axils of one-year-old branchlets. Male and female flowers occur on separate trees, both lacking petals, the minute calyx in four parts, the male typically with 2 or 3 purplish stamens that turn gray after the pollen is dispensed.
Leaves and stems:
Leaves are opposite and pinnately compound, 6 to 12 inches long with 5 to 9 (usually 7) oval to lance-elliptic leaflets. Leaflets are 2½ to 5 inches long and 1 to 1¾ inches wide with a very short (less than ¼ inch) winged stalk, finely toothed edges, and tapering to a pointed tip. The upper surface is dark green and smooth, the lower surface pale green with short hairs either along the midvein and the base of lateral veins, or across entire surface. The pair of leaflets at the base of the leaf are smallest.
Green Ash is a large tree of riparian and upland forest and shelter belts across Minnesota. It is the second most common ash species in Minnesota with an estimated population of over two hundred million trees. The name Red Ash has been applied to those types that have consistently hairy twigs and leaf undersides and was at one time designated as var. pensylvanica, with those with smooth twigs and hairs only on the leaf veins as var. subintegerrima. As this was the only distinction with the two varieties intermixing freely, this classification has fallen out of vogue. Very similar to both Black Ash (Fraxinus nigra) and White Ash (F. americana), Green Ash can easily be distinguished from the other two by its short, winged stalks on the leaflets. In winter, the dormant buds most closely resemble White Ash, with chocolate brown buds and the first two lateral buds tight against the terminal bud, but the leaf scars of the lateral buds are more half moon to oval shaped, broader than White Ash. Black Ash can have similar bud scars but there is always a measurable internode (gap) between the terminal bud and the first two lateral buds below it. Like all ash, it leafs out late and defoliates earlier than most other trees. In the fall it can turn a brilliant, but short lived yellow. It was a highly adaptable urban tree tolerating a wide range of sites, even performing quite well on dry, compacted soils. Inexpensive and easily transplanted, it was used extensively used to replace the vast monoculture of American Elms lost to Dutch elm disease. Unfortunately, it is highly susceptible to the destructive emerald ash borer forcing cities once again to cut down and replace them.
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- Green Ash in a boulevard planting
- twig and bud scars
- crown branches
- turning to fall color
- underside of leaf with 7 leaflets
- early season leaves
- more leaves
- leaflet stalk
- trunk with brownish gray bark
- White, Black and Green Ash leaflet comparison
- White, Black and Green Ash terminal bud comparison
- White, Black and Green Ash leaf scar comparison
- Black and Green Ash samara comparison
Photos courtesy Peter M. Dziuk taken in Anoka, Hennepin and Ramsey counties.
Have you seen this plant in Minnesota, or have any other comments about it?