South Dakota Native Plant Research
Oleaceae: Fraxinus pennsylvanica

Oleaceae: Fraxinus pennsylvanica


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Family Name


Common Name

Green ash

Native American Name

Lakota: pseȟtíŋ čháŋ


Fraxinus pennsylvanica is a large tree reaching 20 m tall with dark gray to brown, furrowed bark. The younger branches go from greenish with white lenticels (pores) to brown to gray and can be smooth to hairy. The petiolate, opposite leaves are compound odd-pinnate,11-30 cm long, with 5-9 leaflets. The leaflets are lanceolate to elliptic, 6-15 cm long and up to 5 cm wide, with short stalks. The first pair of leaflets is usually the shortest. The margins usually have small teeth, the upper surface is dark green and smooth and the lower surface is paler with short hairs along the midvein or across entire surface. The trees are dioecious, having either male or female flowers. The inflorescences consist of panicles, 3-5 cm long, in the axils of leaves on the first year branches. The flowers have an irregularly toothed, cup-shaped calyx, no petals and either 2-3 stamens or a pistil with a long style. The fruit is a tan, narrowly oblanceolate single samara. Green ash blooms in April and May in flood plains, ravines and along stream and lake shores throughout South Dakota.

Additional Notes

Green ash has been planted in windbreaks and urban plantings throughout SD and is an excellent shade tree. Unfortunately, it is under attack by the emerald ash borer and must be closely monitored and treated or it will be killed within 3 years after being infested by the bug.

Horticulture Notes

Seed collection: The samaras remain attached to the tree well into the winter and can be collected any time in late summer or fall.

Germination: The seeds need a 60-day cold moist treatment before spring planting or do well with fall sowing.

Light: Full sun to partial shade.

Soil: Well drained sandy to clay soils.

Water: Moist to mesic.

Oleaceae: Fraxinus pennsylvanica