Green Ash Identification Guide
Recognize green ash by its opposite pinnately compound leaves, diamond-patterned bark, and paddle-shaped winged seeds.
Read the full Green Ash encyclopedia entry →
Key Identifying Features
Green ash (Fraxinus pennsylvanica) is a widely planted, adaptable shade tree of North America, now threatened across its range by the emerald ash borer. Like all ashes, it has opposite, compound leaves.
- Opposite branching and leaf arrangement (rare among trees)
- Pinnately compound leaves with 5-9 leaflets
- Bark with a regular, interlacing diamond-shaped ridge pattern
- Single paddle-shaped winged seeds (samaras) in hanging clusters
Leaves & Stems
Each leaf is 20-30 cm long and pinnately compound, with typically 7 (range 5-9) lance-shaped to elliptical leaflets arranged along a central stalk. Leaflets are 5-12 cm long, tapered at both ends, with finely toothed to nearly smooth margins, green and similar in color on both surfaces (the underside is only slightly paler, unlike white ash which is whitish below). Stalks of the side leaflets are short but distinct. Fall color is yellow.
The key structural clue is opposite arrangement: leaves, buds, and twigs emerge in pairs directly across from each other. Twigs are stout and gray-brown with brown, fuzzy, rounded buds set above crescent-shaped leaf scars. Bark is gray-brown with a tight, regular network of diamond-shaped furrows.
Flowers & Fruit
Green ash is usually dioecious (separate male and female trees). Inconspicuous purplish flowers appear in clusters before or with the leaves in spring. Female trees produce abundant single-winged samaras: a slender seed body with a flat, paddle- or canoe-paddle-shaped wing 3-6 cm long, hanging in dense drooping clusters that persist into winter.
How to Tell It Apart from Look-Alikes
- White ash: Leaflets distinctly whitish below with stalks; leaf scars deeply notched (U-shaped) around the bud; samara wing extends less down the seed body.
- Boxelder (a maple): Also opposite and compound, but with only 3-5 coarsely toothed leaflets and paired (not single) samaras.
- Black walnut / sumac: Compound but arranged alternately, not opposite.
Confirm opposite branching first, then check for whitish leaflet undersides to separate from white ash.
Where You'll Find It
Native to floodplains, riverbanks, and moist bottomlands across central and eastern North America, and historically overplanted as a tough urban street tree. It tolerates wet soils, drought, and pollution but is now widely killed by emerald ash borer.
Quick ID Checklist
- Opposite branching and leaf pairs
- Pinnately compound leaves, usually 7 leaflets
- Leaflet undersides green, not whitish
- Diamond-patterned interlacing bark
- Single paddle-shaped samaras in hanging clusters
Frequently asked questions
How do I know a tree is an ash?
Look for opposite branching plus pinnately compound leaves with 5-9 leaflets and single paddle-shaped winged seeds. Few other trees combine all three.
How is green ash different from white ash?
Green ash leaflet undersides are green and the leaf scar is straight-topped, while white ash leaflets are distinctly whitish below with a deeply notched leaf scar around the bud.
What threatens green ash trees today?
The emerald ash borer, an invasive beetle, has killed millions of ash trees across North America, including green ash.
Could it be confused with a walnut or sumac?
Those also have compound leaves but they are arranged alternately along the twig, while ash leaves are strictly opposite.