black walnut

(Juglans nigra)

Conservation Status

IUCN Red List

not listed

NatureServe

N5 - Secure

SNR - Unranked

Minnesota

not listed

Wetland Indicator Status

Great Plains

FACU - Facultative upland

Midwest

FACU - Facultative upland

Northcentral & Northeast

FACU - Facultative upland

 
black walnut
 
 
Description

Black walnut is a medium-sized, fast-growing, deciduous tree rising on a single trunk. It has a deep, wide-spreading root system and a deep taproot when young. It can be up to 130 tall and 96 in diameter in breast height, though in Minnesota mature trees are usually 50 to 70 tall and 24 to 36 in diameter. It is moderately long-lived, surviving up to 150 years.

The trunk is thick, straight. The lower trunk is free of branches, and the middle and upper trunk develop a few large, ascending branches. In open areas it has an open, rounded crown up to 70 in diameter. Under competition it is taller and has a small, open crown.

The bark on young trees is thin, light brown or light grayish-brown, and scaly. As it matures it becomes moderately thick and divided into ridges and narrow furrows. The ridges are flat-topped, intersect every 12 or less, and are broken horizontally at irregular intervals. The ridges and furrows form a rough diamond () pattern. On mature trees the bark is thick dark brown to grayish-black, and deeply furrowed. The furrows are intersecting and broken horizontally, forming upright and inverted Y and V shapes.

First-year twigs are stout, round in cross section, greenish-brown, and densely covered with both glandular and non-glandular hairs. Second-year twigs are brown or grayish-brown. They are sparsely covered with glandular and non-glandular hairs or are almost hairless. They have scattered, small, slightly raised, pale, corky dots (lenticels). There are no thorns. The pith is buff and appears as thin walls with hollow chambers, looking something like a honeycomb. The leaf scars are broad, conspicuous, raised, and inversely heart-shaped. The upper margin is deeply notched and does not have a ridge of hairs. There are three large, U-shaped clusters of bundle scars. The appearance has been described as three horseshoes or a monkey face.

Terminal buds are egg-shaped to almost globe-shaped, 5 16 to long, slightly flattened, and blunt at the tip. They are covered with a few tan to white, hairy scales. Lateral buds are much smaller.

The leaves are deciduous, alternate, and 8 to 24 long. They are on 1 3 16 to 3½ long, hairy leaf stalks. They are pinnately divided into 14 to 23, usually 15 to 19, leaflets. The terminal leaflet is missing or, if present, is much smaller than the lateral leaflets.

The leaflets are nearly stalkless, egg-shaped to egg lance-shaped, 2¾ to 5½ long, and 1¼ to 2¼ wide. They droop downward from the main axis (rachis) of the compound leaf. They taper to a point at the tip with concave sides along the tip and are rounded or nearly squared and asymmetrical at the base. The upper surface is dark yellowish-green and hairless or sometimes has scattered, head-like bundles of minute, gland-tipped hairs along the midrib. The lower surface is pale green and hairy along the midrib and in the axils of the lateral veins. The hairs on the lower surface are bundled but not branched. The margins are finely toothed with sharp, forward pointing teeth. The leaflets are strongly aromatic when crushed. In autumn the leaves turn yellow.

Male and female flowers are borne on the same branchlet. They appear early May to early June. The male inflorescence is a slender, 1½ to 4 long catkin drooping from the base of previous-year twigs. The female inflorescence is a cluster of 1 to 4 flowers on a short spike at the tip of current-year twigs. The flowers are pollinated by wind.

The fruit is a nut enclosed in a husk appearing singly or in clusters of 2 or 3. The husk is greenish-bronze, thick, more or less globe-shaped, and 1¾ to 2¾ in diameter. It is slightly hairy but not sticky and not covered with glandular hairs. It ripens in late August to late September and is dispersed by animals. The shell of the nut has rounded ridges. The seed is sweet-tasting.

 

Height

50 to 70

 

Record

The champion black walnut in Minnesota is on private property near Oronoco, in Olmsted County. In 1981 it was measured at 112 tall and 213 in circumference (67.8 in diameter), with a crown spread of 110.

 

Flower Color

Green

 

Similar Species

Butternut (Juglans cinerea) has dark brown pith in the twigs. Terminal buds longer, up to long. The leaf scar has a band of hairs above it. The leaves are divided into no more than 17 leaflets. The leaflets are flat, they do not droop downward from the central axis (rachis) of the leaf. The terminal leaflet is present and well developed. The upper side of the leaflet is sparsely to moderately and evenly hairy. The underside is often densely covered with branched hairs. The husk of the fruit is distinctly longer than wide and somewhat pointed, not spherical, and is with glandular hairs making it sticky to the touch. The shell of the nut has irregular, jagged ridges.

Habitat

Rich, well-drained, lowland forest openings. Shade intolerant.

Ecology

Flowering

Early May to early June.

 

Pests and Diseases

 

Use

 

Distribution

Distribution Map

 

Sources

2, 3, 4, 5, 7, 8, 24, 28, 29, 30.

The light green counties on the map represent observations on iNaturalist and repeated on GBIF, many or most of which are on private property and therefore not “outside of cultivation.” The observation in Clay County is from GBIF and is on the campus of Corcordia College, again not “outside of cultivation.”

6/2/2025    
     

Nativity

Native

     

Occurrence

Locally common

Taxonomy

Kingdom

Plantae (green algae and land plants)

Subkingdom

Viridiplantae (green plants)

Infrakingdom

Streptophyta (land plants and green algae)

Superdivision

Embryophyta (land plants)

Division

Tracheophyta (vascular plants)

Subdivision

Spermatophytina (seed plants) / Angiospermae (flowering plants)

Class

Magnoliopsida (dicots)

Subclass

Rosidae

Superorder

Rosanae

Order

Fagales (beeches, oaks, walnuts, and allies)

Family

Juglandaceae (walnut)

Subfamily

Juglandoideae

Tribe

Juglandeae

Subtribe

Juglandinae

Genus

Juglans (walnuts)

Section

Rhysocaryon

   

Subordinate Taxa

Wallia nigra

   

Synonyms

 

   

Common Names

American walnut

black walnut

eastern black walnut

 

 

 

 

 

 

 

 

 

Glossary

Catkin

A slim, cylindrical, drooping cluster of many flowers. The flowers have no petals and are either male or female but not both.

 

Glandular hairs

Hairs spread over aerial vegetation that secrete essential oils. The oils act to protect against herbivores and pathogens or, when on a flower part, attract pollinators. The hairs have a sticky or oily feel.

 

Lenticel

A corky, round or stripe-like, usually raised, pore-like opening in bark that allows for gas exchange.

 

Pinnate

On a compound leaf, having the leaflets arranged on opposite sides of a common stalk. On a bryophyte, having branches evenly arranged on opposite sides of a stem.

 

Pith

The spongy cells in the center of the stem.

 

Rachis

The main axis of a compound leaf, appearing as an extension of the leaf stalk; the main axis of an inflorescence.

Visitor Photos
 

Share your photo of this plant.

 

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach one or more photos and, if you like, a caption.

Randy

black walnut    

Fruit of a black walnut, Freeborn County, MN, July 2017

   
     

Black walnut bark

   
black walnut   black walnut
MinnesotaSeasons.com Photos
black walnut   black walnut

Plant

 

Plant

     
black walnut   black walnut

Plant

 

Male inflorescence

     
black walnut   black walnut

Male inflorescence

 

Male inflorescence

     
black walnut   black walnut

Male inflorescence

 

Male inflorescence

     
black walnut   black walnut

Leaves

 

Leaves

     
black walnut

 

 

 

  black walnut
 

Leaves

 

 

 

 

Leaves

   
     
black walnut   black walnut

Leaflet

 

Fruit

     

 

black walnut   black walnut

Bark

 

Bark

 

Camera

Slideshows

Juglans nigra
Blake C. Willson

Juglans nigra
About

Black Walnut

 

slideshow

Visitor Videos
 

Share your video of this plant.

 

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Attach a video, a YouTube link, or a cloud storage link.

 

 

 
 
Other Videos

Black Walnut identification (Juglans Nigra) video
wvoutdoorman

About

Published on Aug 15, 2012

Helping ID the tree of Black Walnut

How to ID Juglans nigra
Laura Deeter

About

Uploaded on Oct 14, 2008

Key Id Characteristics for identification of Juglans nigra

How to identify a Black Walnut Tree
jyarf

About

Published on Jul 30, 2013

http://www.jyarf.com

How do you identify the black walnut tree? Well watch the video to findout.

Trees with Don Leopold - black walnut
ESFTV

About

Uploaded on Oct 21, 2011

No description available.

The Black Walnut: Trees, Pests & People
Don't Move Firewood

About

Published on Aug 9, 2013

In this chapter of Trees, Pests & People, we look at the threat of thousand cankers disease as it looms from a distance over the Missouri black walnuts.

Trees, Pests & People is the story of three kinds of trees -- Walnut, Avocado and Ash. These trees are united by the threat of invasive insects and diseases -- forest pests from other countries that are killing trees across the nation. But more than the trees, this is the story of how these threats affect everyday lives, and how we can all fight the problem of invasive pests.

This video was made by The Nature Conservancy with funding from USDA-APHIS. For more information on these pests, and what you can do to help, visit www.dontmovefirewood.org.

 

Camcorder

Visitor Sightings
 

Report a sighting of this plant.

 

This button not working for you?
Simply email us at info@MinnesotaSeasons.com.
Be sure to include a location.

Randy
July 2017

Location: Freeborn County, MN

Fruit of a black walnut

black walnut
Randy
11/14/2016

Black walnut bark

black walnut
MinnesotaSeasons.com Sightings

Afton State Park

Baker Park Reserve

Bertram Chain of Lakes Regional Park

Blue Mounds State Park

Brownsville Bluff SNA

Bur Oak WMA

Camden State Park

Cannon River Wilderness Area

Carley State Park

Carpenter St. Croix Valley Nature Center

Cedar Mountain SNA

Cherry Grove Blind Valley SNA

Chimney Rock SNA

Clifton E. French Regional Park

Crystal Spring SNA

Dodge Nature Center

Forestville/Mystery Cave State Park

Fort Ridgely State Park

Franconia Bluffs SNA

Frontenac State Park

Helen Allison Savanna SNA

Hyland Lake Park Reserve

John Murtaugh Memorial WMA

John Peter Hoffman Spring Brook Valley WMA

Keller Regional Park

Kilen Woods State Park

King’s and Queen’s Bluff SNA

Lake Byllesby Regional Park

Lake Louise State Park

Lebanon Hills Regional Park

Leif Mountain

McKnight Prairie

Minneopa State Park

Minnesota Valley State Recreation Area, Lawrence Unit

Mississippi River County Park

Mound Prairie SNA

Myre-Big Island State Park

Ney Nature Center

Oxbow Park & Zollman Zoo

P.N. and G.M. Nelson Wildlife Sanctuary

Pilot Knob

Pine Bend Bluffs SNA

Prairie Bush Clover SNA

Prairie Creek WMA, Koester Prairie Unit

Rice Lake State Park

Ritter Farm Park

River Terrace Prairie SNA

Robert Ney Memorial Park Reserve

Rushford Sand Barrens SNA

St. Croix Savanna SNA

Sakatah Lake State Park

Savage Fen SNA

Seminary Fen SNA

Seven Springs WMA

Shooting Star Prairie SNA

Split Rock Creek State Park

Spring Creek Prairie SNA

Spring Lake Park Reserve

Springbrook Nature Center

Thompson County Park

Townsend Woods SNA

Valley View Park

Whitetail Woods Regional Park

Whitewater State Park

Wild River State Park

Wood-Rill SNA

Woodbury WMA

Zumbro Falls Woods SNA

 

 

Binoculars

 

Created: 8/31/2005

Last Updated:

© MinnesotaSeasons.com. All rights reserved.

About Us

Privacy Policy

Contact Us