Fraxinus spp. Characteristics
Ash trees (Fraxinus spp.) are the only known North American hosts of emerald ash borer (EAB). Ashes have pinnately compound leaves arranged opposite one another on the branch. Each leaf bears five to nine leaflets. The fruit is a winged seed (samara). Some ash species have bark with interlacing ridges that form a diamond-like pattern when mature.
Identification of Emerald Ash Borer
| Once-Compound Leaf original | Oppositely Arranged original |
| Fruit/Seed (samara) original | Bark of White Ash original |
Some Non-hosts of the EAB That Could Be Confused with Ash
- Box-elder (Acer negundo) has pinnately compound leaves with opposite arrangement, but only three to five leaflets per leaf that are somewhat more coarsely toothed.
- Hickories (Carya spp.) and walnuts (Juglans spp.) have pinnately compound leaves with alternate arrangement.
- Buckeye (Aesculus spp.) leaves are arranged oppositely, but are palmately compound (leaflets radiate from a single point).
- Maple (Acer spp.) and dogwood (Cornus spp.) leaves are oppositely arranged but are simple rather than compound.
Resources
- Michigan State University Extension Bulletin "
Distinguishing Ash from Other Common Trees
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." (4 pp, .pdf)