South Dakota Native Plant Research
Juglandaceae : Juglans nigra

Juglandaceae : Juglans nigra


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Family Name


Common Name

Black walnut

Native American Name

Dakota: Hma; Lakota: gmá, čhaŋsápa


Juglans nigra is a large tree with brown bark that grow to 25 m tall with a trunk up to 1 m in diameter in a forest stand. Individual specimens growing under ideal conditions can grow much larger. Young twigs are green and covered with glandular hairs. The alternate, compound palmate leaves grow to 50 cm long, the 11-23 leaflets are sessile, oblong lanceolate, pointed at the tip and usually with small teeth along the margins. The trees are monoecious, with green male flowers in catkins up to 12 cm long, each with about 4 sepals and 8-40 stamens. The female flowers are terminal on new growth in clusters of 1-several flowers, each with 3 small bracts and a hairy pistil with a short style and 2 yellow green stigmas. The fruit is a globose, yellow green turning brown nut, 5 cm in diameter, containing a nut 4 cm in diameter. Black walnut blooms in April and May. This species is native to the southeastern corner of South Dakota, but has been planted in windbreaks and yards state wide, becoming naturalized throughout the state.

Additional Notes

Black walnut is a magnificent tree for South Dakota. Its deep roots and strong wood make it resilient to our climate. The nuts are delicious, if somewhat difficult to open. The bark is used for a black dye and the fruit husks make a colorfast brown dye. It starts to produce fruit at about 12 years and reaches full maturity in about 150 years. The wood is beautiful and is used in furniture construction. The plant produces juglone in all of its tissues. This compound is toxic to many plant species, making it difficult for many garden species to grow near it. Bluegrass is immune and does very well growing underneath.

Horticulture Notes

Seed Collection: Collect seed when they begin to drop to the ground. Use gloves to prevent yellow brown stains.

Germination: The seeds have a hard dormancy. Fall sowing of the dehusked seeds provides good results. Spring sowing requires up to 7 months stratification.

Vegetative Propagation: The roots grow deep very rapidly, making transplanting difficult after the first year or 2 of growth.

Soils: Prefers rich well drained soils.

Light: Full sun

Water: Prefers moist conditions but can tolerate dryer soils.

Juglandaceae : Juglans nigra