Plant
Eastern Black Walnut
Juglans nigraAlso known as American Black Walnut, Black Walnut
Eastern black walnuts dominate rich, moist bottomlands and river valleys throughout eastern North America, growing into tall canopy trees with deeply furrowed dark bark. They produce heavy chemical compounds called juglone through their roots and fallen leaves, inhibiting the growth of competing plants nearby. Squirrels and small mammals play a vital role in forest regeneration by caching and burying the thick-hulled nuts across wide areas.
Canopy TreeDeciduousNative
—observations
—countries
—peak records
Least ConcernConservation statusIUCN Red List categoriesLCNTVUENCREWEXLeast ConcernRed List categories, explained →
Diet & preyAutotrophic (Photosynthetic)
Predators
- Walnut Caterpillar
- Luna Moth Larvae
- Bark Beetles
ThreatsThousand cankers disease, overharvesting for timber, habitat fragmentation
HabitatsRiparian forests, floodplains, rich moist woodlands
Life span150–250 years
Classification
- OrderFagales
- FamilyJuglandaceae
- GenusJuglans
- SpeciesJuglans nigra
Range data is not available yet.
Interaction riskHigh
- Low
- Moderate
- High
- Very high
- Why interaction risk is high
- Roots and hulls contain juglone, which is toxic to horses and dogs; wild nuts have toxic look-alikes.
- Why it is dangerous
- Produces juglone toxin, which causes severe laminitis in horses exposed to walnut sawdust and toxicosis in dogs ingesting moldy hulls.
- How to recognize a risky encounter
- Recognized by dark, deeply diamond-furrowed bark, large compound leaves with 15 to 23 leaflets, and round green fruits.
- What to do
- Keep pets away from fallen rotting nuts and avoid using walnut wood shavings as animal bedding.
Responsible observation
- Gardening Note: Avoid planting susceptible nightshades like tomatoes near the dripline due to soil juglone.
- Wildlife Viewing: Watch fox squirrels and grey squirrels caching fallen green hulls in late autumn.
Seed Disperser (c) Diliff, some rights reserved (CC BY-SA) · cc-by-sa
Host Plant "Lovely luna moth at the Neosho National Fish Hatchery" by U.S. Fish and Wildlife Service - Midwest Region is licensed under CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/. · cc-by
Close Relative (c) Tom Norton, some rights reserved (CC BY) · cc-by
Close Relative (c) Ed Alverson, some rights reserved (CC BY), uploaded by Ed Alverson · cc-by
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