Black Walnut Juglans nigra Linnaeus    Synonyms: Eastern Black Walnut, Wallia nigra.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Juglandales   >   Family Juglandaceae   >   Genus Juglans   

Status:

Black Walnut is one of two native species of walnut; the other is the state-rare species, Butternut, also called White Walnut (Juglans cinerea). Black Walnut is distributed from western Massachusetts to central Nebraska, south to eastern Texas and southern Georgia (Harlow, 1957). The wood is of high commercial value.

Description:

Black Walnut is a medium to large tree, often 50 to 75 feet tall. When growing in a forest, it has a clear straight trunk. Leaves are pinnately compound, with 9-23 leaflets; terminal leaflet usually lacking, in contrast to Butternut, in which a terminal leaflet is usually present (Weakley, et al., 2012). Black Walnut twigs have light yellowish-gray pith, in contrast to the chocolate-colored pith of Butternut; the pith of both species is chambered. Bark of Black Walnut is brown to nearly black, and on mature trees becomes deeply furrowed, with rough ridges. The nut is spherical, in contrast to Butternut's ellipsoidal nut.

Where to find:

Black Walnut grows in rich soil of mesic upland forests, floodplain forests, open fields, and fencerows (Weakley, et al., 2012). It has been recorded from every county in Maryland, but is most common in the northern and western counties. Not frequent on the lower Eastern Shore (Brown and Brown, 1982).

Relationships:

Black Walnut shells produce an allelepathic substance called juglone, which inhibits the growth of plants beneath it.

Has been recorded as a host plant for Banded Hairstreak.

Host plant for various moth species including Luna Moth, Regal Moth, Imperial Moth, Walnut Sphinx Moth, Fall Webworm Moth, Walnut Caloptilia, Pecan Leafminer Moth, Monkey Slug Moth, Skiff Moth, Sad Underwing Moth, Bride Underwing Moth, Penitent Underwing Moth, Yellow-gray Underwing Moth, Widow Underwing Moth, Banded Tussock Moth, Angus's Datana Moth, Walnut Caterpillar Moth, Red-humped Caterpillar Moth, Black-blotched Prominent Moth, Closebanded Yellowhorn Moth, Walnut Shoot Moth, Pecan Leaf Casebearer Moth, American Plum Borer, Hickory Shuckworm Moth, Pecan Bud Moth, Gray-edged Bomolocha Moth, Sleeping Baileya Moth, and Small Baileya Moth.

Decaying shells host the fungus Walnut Mycena (Database of World's Lepidopteran Host Plants).

The fruit fly pest Walnut Husk Maggot feeds on Black Walnut fruit.

Black Walnut is a host plant for the Butternut Woollyworm.

There are 570 records in the project database.

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A fruiting Black Walnut in Prince George's Co., Maryland (9/20/2008). Photo by Jim Brighton. (MBP list)

Black Walnut in Anne Arundel Co., Maryland (5/17/2012). Photo by Bill Harms. (MBP list)

Black Walnut in Anne Arundel Co., Maryland (8/6/2012). Photo by Bill Harms. (MBP list)

Black Walnut in fruit in Harford Co., Maryland (7/23/2017). Photo by Josh Emm. (MBP list)

Black Walnut in Howard Co., Maryland (6/15/2017). Photo by Bill Harms. (MBP list)

Black Walnut in Anne Arundel Co., Maryland (6/29/2017). Photo by Matthew Beziat. (MBP list)

Black Walnut growing in Anne Arundel Co., Maryland (7/19/2019). Photo by Matthew Beziat. (MBP list)

Black Walnut flowers in spring in Montgomery Co., Maryland (4/18/2010). Photo by Janice Browne. (MBP list)

Black Walnut growing in Carroll Co., Maryland (5/20/2018). Photo by Sue Muller. (MBP list)

The state champion Black Walnut at Susquehanna SP in Harford Co., Maryland (9/16/2018). Photo by Bill Hubick. (MBP list)

Trunk of a Black Walnut tree in Howard Co., Maryland (9/8/2013). Photo by Bill Hubick. (MBP list)

Black Walnut in Caroline Co., Maryland (8/2/2016). Photo by Wayne Longbottom. (MBP list)

Black Walnut in Washington Co., Maryland (2/25/2017). Photo by Bill Hill. (MBP list)

Black Walnut (buds) in Dorchester Co., Maryland (2/23/2015). Photo by Jonathan Willey. (MBP list)

Black Walnut in Howard Co., Maryland (2/21/2018). Photo by Sue Muller. (MBP list)

Black Walnut in Montgomery Co., Maryland (5/26/2020). (c) Katja Schulz, some rights reserved (CC BY). Photo by Katja Schulz via iNaturalist. (MBP list)

Black Walnut in Montgomery Co., Maryland (5/26/2020). (c) Katja Schulz, some rights reserved (CC BY). Photo by Katja Schulz via iNaturalist. (MBP list)

Black Walnut (close-up of female) in Howard Co., Maryland (6/1/2017). Photo by USGS PWRC. (MBP list)

Black Walnut in Montgomery Co., Maryland (5/26/2020). (c) Katja Schulz, some rights reserved (CC BY). Photo by Katja Schulz via iNaturalist. (MBP list)

Black Walnut in Montgomery Co., Maryland (6/15/2019). Photo by Jane Hill. (MBP list)

Black Walnut in Howard Co., Maryland (5/10/2017). Photo by Bill Harms. (MBP list)

Black Walnut in Baltimore City, Maryland (5/11/2019). (c) Charlie Davis, some rights reserved (CC BY-NC). Photo by Charlie Davis. (MBP list)

Black Walnut in Baltimore City, Maryland (5/11/2019). (c) Charlie Davis, some rights reserved (CC BY-NC). Photo by Charlie Davis. (MBP list)

Black Walnut in Queen Anne's Co., Maryland (8/13/2019). (c) Wayne Longbottom, some rights reserved (CC BY-NC). Photo by Wayne Longbottom. (MBP list)

A double nut from a Black Walnut in Dorchester Co., Maryland (9/10/2017). Photo by Jim Brighton. (MBP list)

Black Walnut in Allegany Co., Maryland (2/25/2018). Photo by Sue Muller. (MBP list)


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