butternut

(Juglans cinerea)

               
Conservation Status

IUCN Red List

not yet assessed

butternut

NatureServe

N3N4 - Vulnerable to Apparently Secure

S3 - Vulnerable

Minnesota

Endangered

Wetland
Indicator
Status

Midwest

FACU - Facultative upland

Northcentral & Northeast

FACU - Facultative upland

Nativity

Native

 
Occurrence

Uncommon

 
Habitat

Streambanks and hillsides in mixed hardwood forests. Shade intolerant.

 
Flowering

Early May to early June

     
Flower Color

Green

     
Height

40 to 60

     

Identification

This is a fast-growing deciduous tree rising on a single trunk. On deep soils the root system includes a taproot and deep, widely spreading lateral anchors. In shallow soils there is no taproot. In Minnesota mature trees are usually 40 to 60 tall and up to 25 in diameter at breast height, though large individuals can reach over 80 in height and 36 in diameter. It is short-lived due to susceptibility to root diseases, decays, fungal infection, and invasion by wood-boring insects. The greatest recorded age in Minnesota was 221 years, but it usually does not live more than 75 years.

The trunk is slender and often crooked. It is often short and forked or divided into a few large, ascending branches. The crown is broad, open, and rounded on top.

The bark on young trees is light gray and smooth. On mature trees the bark is gray to grayish-brown, moderately thick, with irregular, broad, flat-topped, smooth, interlacing ridges and broad, shallow, dark fissures.

First-year twigs are stout, green to greenish-brown, and hairy, with small, slightly raised, pale, corky bumps (lenticels). Second-year twigs are stout, green to greenish-brown, and hairless. The pith is finely chambered and dark, chocolate brown. Cut through a twig at an angle and check the pith. If it consists of walls with hollow chambers, looking something like a honeycomb, then the tree is either black walnut or butternut. The leaf scars are raised and inversely heart-shaped. The upper margin is flat or almost flat and has a dense ridge of tan, velvety hairs. There are 3 clusters of bundle scars. The appearance is that of a monkey face with a tan eyebrow.

Terminal buds are pale yellow, cone-shaped, flattened, 5 16 to long, to 3 16 wide, and covered by a few hairy scales. Lateral buds are smaller and are covered with short, soft, matted, woolly, rusty-brown, hairs.

The leaves are deciduous, alternate, 15 to 24 long, and pinnately divided into 11 to 17 leaflets. They are on 13 16 to 3½ long, hairy leaf stalks. The terminal leaflet is present and well developed.

The leaflets are nearly stalkless, egg-shaped to oblong lance-shaped, 2¾ to 5 long, and 1 to 2 wide. 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 yellowish-green, wrinkled, rough and sparsely to moderately but evenly hairy. The lower surface is paler, grayish-green, and densely soft-hairy. The terminal leaflet is usually present, well developed, and is about the same size as the 2 adjacent lateral leaflets. The margins are finely toothed with sharp, forward pointing teeth. In autumn the leaves turn yellow or brown. The leaflets are flat, they do not droop downward from the central axis (rachis) of the leaf.

Male and female flowers are borne on the same branchlet. They appear early May to early June. The male inflorescence is a slender, 2 to 4¾ long catkin drooping from the base of previous-year twigs. The female inflorescence is a cluster of 3 to 7 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 to 5. The husk is greenish-bronze, thin, oblong to egg-shaped, 2 to 3 long, and 1 to 1½ wide. It is obviously longer than wide and somewhat pointed at one end. It is covered with glandular hairs making it sticky to the touch. It ripens in early August to early September and is dispersed by animals. The shell of the nut has irregular, jagged ridges. The seed is sweet-tasting.

 
Record

The champion butternut in Minnesota is on city property in Roseville, in Ramsey County. In 2004 it was measured at 95 tall and 206 in circumference (65½ in diameter).

 
Similar
Species

Black walnut (Juglans nigra) has buff pith in the twigs. The terminal buds are shorter, 3 16 to 5 16 long. The leaves are divided into up to 23, usually 15 to 19, leaflets. The leaflets droop downward from the rachis. The terminal leaflet is either poorly formed or missing. The leaf scar is deeply notched at the top, not almost straight across, and does not have a band of hairs above it. The upper surface of the leaf is either hairless or has hairs only along the midvein. The fruit is nearly spherical and is not sticky to the touch.

 
Pests and Diseases

Butternut Canker (Sirococcus clavigignenti-juglandacearum)


Distribution Distribution Map   Sources: 2, 3, 4, 5, 6, 7, 8, 24, 28.

Comments

Butternut Canker
Throughout its range butternut is being killed Butternut Canker. There is no known cure and it is not known if any trees are resistant to the fungus.


Taxonomy

Family:

Juglandaceae (walnut)

 

Genus:

Juglans

 

Section:

Trachycaryon

 
Synonyms

Wallia cinerea

 
Common
Names

butternut

white 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

Having the leaflets of a compound leaf arranged on opposite sides of a common stalk.

 

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.

       

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Randy


Butternut, July 2017, Freeborn County, MN

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Other Videos

 
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Published on Aug 12, 2012

White Walnut identification ( Juglans Cinera ) video : helping ID the tree

 
     
  Trees with Don Leopold - butternut
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Published on Jun 12, 2012

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