Fraxinus pennsylvanica (Green Ash)

Plant Info
Also known as:
Genus:Fraxinus
Family:Oleaceae (Olive)
Life cycle:perennial woody
Origin:native
Habitat:sun; average to moist; forests, floodplains, old fields and field edges
Bloom season:May - June
Plant height:50 to 110 feet
Wetland Indicator Status:GP: FAC MW: FACW NCNE: FACW
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct Cluster type: panicle

[photo of male flowers] 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.

[photo of female flowers] Female flowers have only a single long style emerging from the tiny, green calyx. Flowers emerge before the leaves in spring.

Leaves and stems: Leaf attachment: opposite Leaf type: compound

[photo of leaf with 9 leaflets] 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.

[photo of trunk, gray bark] Branchlets are green to brown, smooth or hairy, with white lenticels (pores) the first year. Branches turn brownish gray, the bark with woven, diamond shaped blocky ridges with deep furrows between.

Fruit: Fruit type: seed without plume

[photo of fruit] Fruit is a single, spatula shaped, winged seed (samara), 1 to 1¾ inch long and ¼+ inch wide, in open dangling clusters that can persist on the tree all winter.

Notes:

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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More photos

Photos courtesy Peter M. Dziuk taken in Anoka, Hennepin and Ramsey counties.

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