// SPECIES PROFILE · TREE · NATIVE

Black Walnut

Juglans nigra

Black walnut is the queen of native hardwoods — straight-grained chocolate-brown lumber, rich edible nuts inside iron-hard hulls, and pinnate compound leaves that cast dappled summer shade. Wild trees line every bottomland creek in NE Oklahoma.

// QUICK FACTS

Family: Juglandaceae
Group: tree
Native range: E. & C. US; common in OK floodplains and rich slopes
USDA hardiness: Zones 4–9
Mature size: 70–100 ft
Sun: Full sun
Water: Deep, moist, well-drained soils
Wildlife value: Squirrel-cached nuts; host to walnut sphinx and luna moth
Ecological role: premier hardwood · edible nut · juglone allelopath

Black Walnut (Juglans nigra) — *Juglans nigra*. Photo via Wikipedia / Wikimedia Commons.

Field Notes

[ growing · ecology · siting · care ]

Plant well clear of vegetable gardens and tomato beds: roots produce juglone, an allelopathic compound that suppresses many susceptible plants within ~50 ft. Tough natives like elderberry, paw-paw, and most grasses are unaffected and make excellent companions.

Why it's on this list: premier hardwood · edible nut · juglone allelopath. Part of Rooted Revival's NE Oklahoma plant catalog — natives, ecologically positive non-invasive cultivars, and food crops worth growing in the Tulsa region.

Companion Planting

[ guild · polyculture · cross-layer pairings ]

Along a stream or seasonal floodplain, black walnut pairs naturally with: american elderberry (Sambucus canadensis), maypop / passionflower (Passiflora incarnata), cardinal flower (Lobelia cardinalis), eastern gamagrass (Tripsacum dactyloides), cosmos (Cosmos bipinnatus), and kentucky coffeetree (Gymnocladus dioicus).

black walnut works best as a canopy or sub-canopy partner above the herbaceous and shrub layers.

Photo Reference

// Juglans nigra — eastern black walnut
Photo: bbooth27 (iNaturalist, CC-BY-NC)