Fraxinus pennsylvanica

Green Ash

Green Ash
Photo courtesy Wisconsin State Herbarium and Kitty Kohout

Flora, fauna, earth, and sky...
The natural history of the northwoods


  • Fraxinus, from the Latin for ash tree
  • pennsylvanica, from the Latin, "of Pennsylvania"
  • Common Name from an apparent lack of creativity in the naming of North American Ash species.
  • Other common names include Darlington Ash, Red Ash, Swamp Ash, Water Ash, White Ash


  • Kingdom Plantae, the Plants
    • Division Magnoliophyta, the Angiosperms (flowering plants)
      • Class Magnoliopsida, the Dicotyledons
      • Subclass Asteridae
        • Order Scrophulariales
          • Family Oleaceae, the Olives
            • Genus Fraxinus, the Ashes
  • Taxonomic Serial Number: 32929
  • Also known as Fraxinus campestris, Fraxinus darlingtonii, Fraxinus lanceolata, Fraxinus smallii


  • Dioecious, deciduous tree with large, straight trunk and high branches.
  • Height to 66' with diameter of 1.5'-2'
  • Leaves opposite and oddly-pinnate, 8"-12", with 5-9 (usually 7) oblong-lanceolate or elliptic, serrate or entire leaflets.
  • Flowers unisexual, borne over the entire outer part of the crown, usually beginning when trees are 3"-4" in diameter and 20' high.
  • Fruit an elongated, winged, single-seeded samara borne in clusters; large seed crops produced each year.
  • Root system extensive, moderately shallow, highly windfirm.
  • Bark dark grey to brown with shallow furrows
  • Wood heavy, hard, strong and yellowish with wide, white sapwood.



  • Most widely distributed of the American ashes, from Cape Breton Island and Nova Scotia to SE Alberta and Montana, and southward to central Texas and northern Florida.


  • Almost completely confined to bottomland sites, but grows well when planted on moist upland soils. Most commonly found on alluvial soils along rivers and streams and less frequently in swamps. Flood tolerant; common on land subject to flooding once or twice a year, remaining healthy when flooded up to 40% of the growing season.
  • Insects: oyster scale; carpenter worm; two ash saw flies; and borers particularly affect shade trees and windbreak plantings.
  • Disease: fungus, athracnose, rusts, and root rot sometimes damage trees and wood.
  • Soils: occurs on a wide variety of soils, surviving best on deep, permeable, well-drained loams. Tolerant of moderately acidic (pH 4.0) to moderately basic soils.


  • Tolerant of burning and is stimulated to sprout from the root crown following damage from fire within the first year of the burn; however its ability to resprout decreases with age and with diameter.
  • Although vegetative reproduction appears to be the primary mode of regeneration after fire due to ability to sprout prolifically after damage, it is also expected that, as a prolific seeder, it will regenerate from seed.



  • During the last Ice Age retreated with other hardwoods to the relative shelter of the lower Mississippi Valley, moving north after the pioneering conifers as the ice sheets melted.


  • Wood heavy, hard, strong and yellowish with wide, white sapwood. Has moderately high specific gravity and a low wood moisture content which make it a valued species for solid wood products as well as for pulp and paper requiring hardwood fibers. Crating, boxing, handle stock and rough lumber can be obtained from merchantable-size trees.
  • Cultivated ornamental throughout its range; often planted for shade and landscape beautification in urban parks, recreation areas, and residential areas. Its leaves turn golden yellow in the fall.


  • Regenerates both through sexual and vegetative reproduction, often regenerating profusely from either seed or vegetatively after disturbance.
  • Large seed crops are produced each year, and the winged samaras are wind-dispersed, most within a few hundred feet of the parent tree.
  • Seeds drop during the fall and winter months and germinate the following spring on a variety of ground types including moist litter as well as mineral soil, but rarely in dense vegetation.
  • Grows best in partial shade.
  • Sprouts readily from root crown or stumps following damage; the ability to sprout decreasing with age and diameter.


  • Cuttings made from young trees root easily under greenhouse conditions. Can also be bench or field grafted.
  • Seed should be harvested in the fall when the color fades from yellow to brown or when the seed within is white, crisp, firm, and fully elongated.
  • Seeds should be spread in shallow layers for complete drying; dewinging is not necessary. May be stored in sealed containers for up to seven years at refrigerator temperatures (40 F) without losing viability.
  • Select seed or plants of the same geographical origin as the planting site, as a large variation in drought and cold-tolerance is encountered in this widely distributed species.
  • Seeds may be sown in the fall without any stratification, by planting them as soon as collected, before October 15, and mulching overwinter with burlap or straw. Spring planted seed requires a warm-cold stratification of 60 days at 32 to 41 F.
  • Germination is about 75% with stratified seed, in 20 days.


  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultivars and species available by mail order from specialty suppliers or at local nurseries
  • Intolerant to moderately tolerant of shade.
  • Oyster shell scale and borers are the most serious potential insect problems. Leaf miners and ash sawflies may occur in some areas. Potential diseases include fungal leaf spot and canker. Brittle branches are susceptible to damage from high winds and snow/ice.



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Last updated on 4 March, 2006