Juglans nigra (Black Walnut)
| Also known as: | |
|---|---|
| Genus: | Juglans |
| Family: | Juglandaceae (Walnut) |
| Life cycle: | perennial woody |
| Origin: | native |
| Habitat: | part shade, sun; average moisture; hardwood and mixed forest, savannas, banks |
| Bloom season: | May - June |
| Plant height: | to 130 feet |
| Wetland Indicator Status: | GP: FACU MW: FACU NCNE: FACU |
| MN county distribution (click map to enlarge): |  |
| National distribution (click map to enlarge): |  |
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Detailed Information
Flower: 
![[photo of male catkins]](/udata/r9ndp23q/pd3/juglans-nigra-12.jpg)
Male and female flowers are borne separately on the same branch (monoecious). Male flowers are in clusters called catkins, 2 to 4 inches long, pendulous in flower, single in the leaf axils of 1 year old branchlets, the flowers yellowish to green with up to 50 stamens per flower.
![[photo of female flowers (past anthesis)]](/udata/r9ndp23q/pd3/juglans-nigra-14.jpg)
Female flowers are in a short spike at the tip of this year's new branchlets with 1 to 4 flowers in the spike, the flowers with a stout, green ovary covered in sticky hairs and a pair of broad, spreading, red-tinged stigma at the top.
Leaves and stems:
![[scan of leaf]](/udata/r9ndp23q/pd3/juglans-nigra-9045389.jpg)
Leaves are alternate, usually crowded at branch tips and appearing whorled, 8 to 24 inches long, compound with 12 to 19 leaflets. Leaflets are lance-oblong, 2¼ to 6 inches long, ½ to 2 inches wide, finely toothed around the edges, with an abrupt taper to a pointed tip, asymmetrical and rounded to straight across at base, and very short-stalked. The terminal leaflet is rather smaller than the lateral leaflets and often absent altogether. The upper surface is dark green and sparsely hairy, the lower is paler in color and covered in a mix of glandular and non-glandular hairs. The compound leaf stalk is green and covered in sticky hairs.
![[photo of twig and buds]](/udata/r9ndp23q/contrib/juglans-nigra-bud-stem-hh.jpg)
Buds are light brown and covered in short fuzz, the terminal bud round to oval and slightly flattened. New twigs are green to olive-brown, variously covered in a mix of glandular and non-glandular hairs, becoming smooth the second year. Leaf scars are more or less Y or heart-shaped with a notch at the tip. Branch pith is chambered and light brown.
![[photo of mature trunk]](/udata/r9ndp23q/trees/juglans-nigra-black-walnut_0524_163015.jpg)
Older bark is dark gray to gray-brown, developing narrow, rough ridges and deep furrows with age. Trunks can reach up to 3+ feet diameter at breast height (dbh).
Fruit:
![[photo of fruit]](/udata/r9ndp23q/pd3/juglans-nigra-2.jpg)
Fruit is usually spherical, 1½ to 3 inches in diameter, about as long as wide, the outer husk greenish and not sticky. Inside is a sweet nut with a hard shell. Fruits are usually single or in pairs at branch tips.
Notes:
Black Walnut is a common forest species in the eastern half of North America and reaches the northern edge of its range in Minnesota. It is prized both for its wood, used for furniture and veneers, as well as the tasty nuts. The natural range extends to Twin Cities area, but it's also been planted much farther north and can be seen in landscapes and parks into the Arrowhead region. In recent years it has fallen prey to Thousand Cankers, a fungal disease primarily spread by the walnut twig beetle, which has spread throughout the western US with a second infection from the mid-Atlantic states into Indiana. The disease is not known to be in Minnesota or surrounding states at this time, but it is heading our way. Black Walnut closely resembles the related Butternut (Juglans cinerea), which is distinguished by more elongated, sticky, oval-elliptic fruits that are usually clustered 3 to 5, dark brown pith in the twigs, the leaflet hairs are branched, the terminal leaflet is about the same size as lateral leaflets, and leaf scars are flatish to convex at the tip and have a band of velvety hairs along the top edge. Black Walnut fruits can also stain your hands black, and broken twigs and crushed leaves give off a strong, pungent odor. Butternut does neither of these.
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More photos
Black Walnut tree
Black Walnut tree
fall color
leaves appear whorled at branch tips
glandular hairs on leaf stalks
comparison of Juglans cinerea and Juglans nigra leaf scars
comparison of Juglans cinerea and Juglans nigra pith
Black Walnut tree
Black Walnut tree
fall color
leaves appear whorled at branch tips
glandular hairs on leaf stalks
comparison of Juglans cinerea and Juglans nigra leaf scars
comparison of Juglans cinerea and Juglans nigra pithPhotos by K. Chayka taken in Ramsey County. Photos courtesy Peter M. Dziuk taken at various locations in the Twin Cities metro area. Other photos courtesy Heather Holm.
Comments
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2018-10-17 12:48:55
Except for one instance in the vicinity of Echo Lake, these are all planted yard trees. Seems the species can grow much further north in the state.
on: 2020-05-27 12:09:58
there is one growing just north of where hwys 71 and 72 split in a common area along the public walking path. i have gathered the nuts for a couple of years to try to establish on my property in Saum, mn. but have seen no seedlings yet.
on: 2020-07-26 11:15:30
I think I have a Black Walnut tree growing outside my kitchen window. It has 1 'fruit/nut' growing on it (almost looks like a small green apple). This is the first year I've seen fruit growing on it and about the 3rd year it's been growing in this spot.
on: 2020-10-28 09:46:29
There are a couple of small to medium walnut trees in our neighborhood that produce some nuts. Squirrels have distributed these nuts far and wide. Seedlings and small trees now appear wherever space is undisturbed. We have a walnut tree about 15 feet tall and narrow: 1 1/2 inches at breast height. The lowest branches are 9 feet from the ground. I found it when clearing out a patch of buckthorn. I am interested in seeing how it branches out now that the competition for light and water is lessened.
on: 2021-05-10 17:14:02
The farm I grew up on near St. Cloud MN had a mature black walnut tree on it (only one on the 160 acre property) that was over 100 feet tall in the 1950's. When it began to die, my dad had it cut, saved the timber and had a gunstock made from a portion of it. The land was homesteaded 100 years prior. Because the tree was near the house, we wondered it it was planted when homesteaded, or if it was native to the land.
on: 2021-06-21 18:31:25
An industrious squirrel buried numerous black walnuts in our rhubarb patch last fall. I yanked out several small saplings this morning only to notice this afternoon I had missed several others.
on: 2022-03-16 03:19:45
My mother died in 2017 at 101 yo. The tree was large when her parents homesteaded the farm in 1910.. The tree has lost 1/2 its mass when it finally split apart. A chain kept the 2 main parts together for 60+ yrs. A chain swing was attached more than 20' up. The farm yard is part of a terminal moraine. Northern edge of the Big Woods. My father planted Black Walnuts from Winona County 50+ yrs ago on nearby woodlot. Still small due to short growing season, climate at northern limit of range.I see the range map does not show a Black Walnut in the OtterTail/Todd County area.
on: 2022-03-16 09:26:47
Mark, a lone tree on an old homestead was more likely planted rather than naturally occurring, but we'll never know for sure. The next closest report is from SW Benton County, on an island in the Mississippi River. Having said that, we are aware disjunct populations of several other species exist, so anything is possible.
on: 2022-07-17 21:39:42
Growing in the ditch between railroad tracks and street.
on: 2022-07-24 20:03:37
We have a walnut tree next to our house with a diameter nearly 40" and a canopy of 80 feet or more Using the age calculators available it's age is over 170 years If that's so is was 60 when the house was built could this be true? It's a beautiful tree even with the mess of the nuts
on: 2022-08-01 16:18:18
We have several fruiting black walnut trees on our property. They are fairly young, maybe 12-15 years old. They weren't planted, we've lived there for 30 years.
on: 2023-08-12 08:39:58
I have two Black Walnuts growing about 3 feet from a storm water pond in a wild area, and both are quite young, 6-12' tall. One of them is growing quite close to a Peach leaved Willow, and several branches on that side of the willow are dieing. The willow is quite large, and possible near the end of its life span, but the non-walnut side is looking very healthy. Should I remove the walnut? Thanks
on: 2023-08-12 08:47:06
Jerome, you might consult with an arborist, or perhaps Ask a Master Gardener.