Identification of Butternuts and Butternut Hybrids

Identication of Butternuts

and Butternut Hybrids

Lenny Farlee

1,3

, Keith Woeste

, Michael Ostry

, James McKenna

and Sally Weeks

USDA Forest Service Hardwood Tree Improvement and Regeneration Center, Purdue University, 715 W. State Street,

West Lafayette, IN, 47907

USDA Forest Service Northern Research Station, 1561 Lindig Ave. St. Paul, MN 55108

Department of Forestry and Natural Resources, Purdue University, 715 W. State Street, West Lafayette, IN, 47907

Purdue University Cooperative Extension Service • West Lafayette, Indiana

PURDUE UNIVERSITY

Purdue University

Forestry and Natural Resources

FNR-420-W

Purdue e xtension

Introduction

Butternut (

Juglans cinerea

), also known as white

walnut, is a native hardwood related to black walnut

(

Juglans nigra

) and other members of the walnut family.

Butternut is a medium-sized tree with alternate, pinnately

compound leaves that bears large, sharply ridged and

corrugated, elongated, cylindrical nuts born inside sticky

green hulls that earned it the nickname lemon-nut (Rink,

1990). The nuts are a preferred food of squirrels and

other wildlife. Butternuts were collected and eaten by

Native Americans (Waugh, 1916; Hamel and Chiltoskey,

1975) and early settlers, who also valued butternut for

its workable, medium brown-colored wood (Kellogg,

1919), and as a source of medicine (Johnson, 1884), dyes

(Hamel and Chiltoskey, 1975), and sap sugar.

Butternut’s native range extends over the entire north-

eastern quarter of the United States, including many

states immediately west of the Mississippi River, and

into Canada. Butternut is more cold-tolerant than black

walnut, and it grows as far north as the Upper Peninsula

of Michigan, New Brunswick, southern Quebec, and

Ontario (Fig.1). Butternut is now threatened everywhere

by a fungal canker disease Sirococcus clavigignenti-jug-

landacearum (Sc-j) (Nair et al., 1979) known as “butter-

nut canker,” and in many places it is rare. When present,

it grows in widely scattered clusters on rich, loamy soils

and on stream terraces; it can also compete on rocky,

drier soils, and slopes (Goodrich, 1838; Johnston, 1851;

Rink, 1990). Historical records indicate that butternut

trees were once much more common than they are today

(Johnson, 1884; Larsen, 1942) and that they may be able

to occupy more habitats than those on which they are cur-

rently found.

Accurate identication of butternuts is an impor-

tant part of the effort to conserve and manage this ne

hardwood tree. Many landowners and resource profes-

sionals are now unfamiliar with the native butternut tree

due to its increasing rarity in the landscape. Reliable

identication has been complicated by the presence of

hybrid trees, propagated primarily for nut production,

and naturally occurring hybrids and backcrosses between

butternuts and introduced Asian walnuts, primarily the

Japanese walnut (

Juglans ailantifolia

This publication will provide guidance for recognizing

butternut trees and possible hybrids to resource profes-

sionals, nut growers, and other citizens interested in

butternuts. A companion publication,

Conservation and

Management of Butternuts,

FNR-421, provides infor-

mation for the propagation and management of butternut

trees, in hopes that landowners and resource managers

who encounter butternuts can help in the effort to con-

serve this tree in the eastern hardwood forest.

Figure 1. Native range of butternut (Juglans cinerea L.).

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

Identifying Butternuts and

Butternut Hybrids

The butternut is relatively easy to distinguish from

black walnut and other native species. All walnut spe-

cies have chambered pith in the center of the twigs. The

pith in a butternut branch is dark chocolate-brown in

color (Fig. 2A), and a butternut leaf scar is surmounted

by a thick band of hairs that resemble a moustache (Fig.

2B, C). Black walnut twigs have light brown pith, and

their leaf scars have no moustaches (Fig. 3). Mature

butternut bark is platy and ash-gray with dark gray s-

sures between the platy ridges. The bark of young trees

is smooth and gray or greenish-gray (Fig. 4). Mature

black walnut bark is dark brown and heavily ridged or

blocky. The bark of young black walnut is brown and

ridged or aky (Fig. 5). Some butternuts have very dark

gray bark that closely resembles bark of black walnuts,

(Ostry and Woeste, 2004) but it usually retains the light

gray, platy surfaces on the top of bark ridges (Fig. 6). The

fruit of a butternut is generally more elongated than the

round-shaped fruit of a black walnut and is covered with

sticky hairs (Fig. 7, 8). Pecan trees and other hickories

are sometimes misidentied as butternuts. Hickories have

leaets that become progressively larger as they approach

the end of the compound leaf (Fig. 9), and the nuts are

enclosed in woody husks that split along four obvious

sutures or seams. They also lack the moustache-like hairs

found above butternut leaf scars.

Identifying a pure butternut tree can be difcult, be-

cause butternuts have hybridized with Japanese walnuts,

and butternut hybrids have been unknowingly planted for

decades. Japanese walnut trees were introduced into the

United States in the mid to late 1800s as a potential nut

crop for the northern states due to their vigor and cold

hardiness (Crane and Reed, 1937). Some varieties of

Japanese walnut have smooth and attened, heart-shaped

nuts, the basis for their common name of “heartnut.”

Other Japanese walnuts have shells similar in texture to

English or Persian walnuts (

J. regia

) (Fig. 14). But-

ternuts can naturally hybridize with Japanese walnuts to

produce vigorous F1 (rst generation) hybrids, known in

horticulture as

. ×

bixbyi

, but commonly called “buarts”

(pronounced “bew-arts”) by nut growers (Bixby, 1919;

McKay, 1945). F1 buart hybrids have also been called

butter-japs, or buartnuts (USDA, ARS National Genetic

Resources Program).

Many F1 interspecic (the rst cross of two species)

hybrids of walnut species have been described around the

world. All of them have hybrid vigor, which means the

Figure 2. Branch traits that distinguish butternuts from

hybrids. Pith color of Japanese walnut (upper), hybrid tree

(middle) and butternut (lower) (A); leaf scar, dormant buds

and lenticels of butternut (left) and a hybrid (right) showing

hairy moustache above the leaf scar, and the notch in the

leaf scar of the hybrid (B), round lenticels and brown twig

color on butternut (C), elongated lenticels and green or tan

twig color often found in hybrids (D).

Photos A and B, Keith Woeste, HTIRC, U.S. Forest Service.

Photos C and D, Lenny Farlee, HTIRC, Purdue University.

Figure 3. Black walnut

lacks the “moustache” of

dense hairs above the leaf

scar found on butternuts

and hybrids.

Photo: Sally Weeks, Purdue

University

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

offspring grow faster than either of the two parent spe-

cies. Nearly all of these F1 hybrids are almost completely

sterile (McKay, 1945). Factors such as lack of pollen pro-

duction, and premature catkin and female ower abscis-

sion lead to little or no seed set. Among walnut hybrids,

buarts are unusual in that they are fertile and can produce

a remarkable number of nuts. Another characteristic of

the walnut family is self-compatibility, which means

an individual tree can pollinate itself. Once buart trees

mature, it is very likely that some buarts pollinate other

buarts, some self-pollinate, and others are pollinated by

pure butternut pollen. Thus, buarts (strictly dened as

F1s) are not nearly as common today as are seedling de-

rivatives of buarts that have a more complicated genetic

heritage. For this reason, we refer to trees with compli-

cated, multi-species genetic background as “hybrids,”

and reserve the term buart for the cases where a tree is

known to be the direct product of a Japanese walnut ×

butternut cross (an

F1), or a tree of this type that has been

maintained by grafting. There are several buart cultivars

propagated by nut growers in North America.

Figure 4. Flat gray plates and darker ssures typical of

mature butternut bark (A), and light bark plates and tan

or even pinkish ssures typical of mature butternut hybrids

(B). The bark of a young, vigorously growing butternut (C)

and a hybrid butternut (D) is similar in appearance. Photos

A, C, D, Lenny Farlee, HTIRC, Purdue University.

Photo B, Keith Woeste, HTIRC, U. S. Forest Service.

Figure 5. Bark of mature black walnut (A), and bark of

young black walnut (B).

Photo A, Sally Weeks, Purdue University, Photo B, Lenny Farlee,

HTIRC, Purdue University

Figure 6. The butternut on the left shows typical light gray

bark, while the butternut on the right displays the less com-

mon dark gray bark, similar to black walnut.

Photo: James McKenna, HTIRC, U.S. Forest Service

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

Besides hybrid vigor and high yielding potential,

buarts and the more complex hybrids derived from them

have inherited some resistance to the butternut canker

fungus from Japanese walnut (Ostry, 1997). Since the

introduction of Japanese walnut, several generations of

butternut hybrids have naturally developed, and hybrid

butternuts have become more numerous across the land-

scape (Hoban et al., 2009) as natural selection left behind

hybrid trees that resisted butternut canker disease where

pure butternuts were killed by the butternut canker. As

butternut hybrids became more prevalent, more hybrid

seed was collected and propagated. In some cases, due

to mistaken identication, hybrids were propagated and

distributed as butternuts, leading to increased distribu-

tion of hybrid trees and confusion about the identity of

the butternut. In some parts of the United States today,

hybrids are virtually the only “butternuts” to be found.

The complex hybrids found today can be challenging

to identify in the eld because they present a mixture of

butternut and Japanese walnut characteristics, especially

Figure 7. Butternut fruits (A) and butternut seeds (B, upper

row). Hybrid seeds are in the bottom row (B). Grid = 1 cm

Photo A, E. Hayes and M. Ostry, U.S. Forest Service, Photo B,

Keith Woeste, HTIRC, U.S. Forest Service

Figure 8. Black walnut fruit (A) and seed (B).

Photo A, Mark V. Coggeshall, Photo B, Sally Weeks,

Purdue University

Figure 9. Butternut leaves (left) normally have 9 to 17

leaets and leaets tend to be largest in the central part of

the leaf. Hickory leaves (right) normally have 9 or fewer

leaets and leaets become progressively larger toward the

end of the leaf. A pecan leaf may have more than 9 leaets,

but these will also be largest near the end of the leaf.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 10. A hybrid

butternut leaf (left) tends

to be larger and longer,

sometimes over 18 inches

long, as compared to a

butternut leaf (right).

Photo: James McKenna,

HTIRC, U.S. Forest Service

Figure 11. Pure butternuts (left) have dropped all foliage

while hybrid butternuts (right) still retain leaves in this

mid-October photo from Tippecanoe County, Indiana.

Photo: Lenny Farlee, HTIRC, Purdue University

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

Table 1. Summary of characteristics of pure butternut and hybrid butternuts.

1-Year Twigs

Butternut Characteristics Butternut Hybrid Characteristics

Current-year stem color

Olive green changing to red-brown near terminal

buds; glossy, few hairs except immediately

beneath terminal buds.

Bright green to copper brown or tan, often densely

covered with rust or tan hairs, especially near

terminal buds. Pale green near terminal bud.

Terminal bud

Whitish to beige in color; narrower, the outer,

eshy scales more tightly compact and bud

longer than hybrids.

Pale green to tan or yellowish in color, often

pyramidal in shape, wider and squatter than

butternut. Outer eshy scales more divergent than

butternut and often deciduous.

Lateral bud

Vegetative buds are elongated and somewhat

angular, creamy white to beige in color.

Vegetative buds are rounded, and green to greenish

brown in color.

Lenticels

Small, round, abundant, evenly distributed,

sometimes elongating horizontally across the

branch (perpendicular to the stem axis).

Large, often elongating laterally down the branch

(parallel to the stem axis) on 1-year wood, patchy

distribution. On 3- and 4-year wood, lenticels often

form a diamond pattern as they become stretched

both transversely and longitudinally.

Leaf scar

Top edge almost always straight or slightly convex;

scar usually more compact.

Top edge almost always notched; often with large,

exaggerated lobes.

Pith Very dark brown.

Variable, dark brown, but more commonly medium

brown or even light brown.

Mature Tree

Bark

Varies from light grey and platy to dark grey and

diamond-patterned in mature trees. In older trees,

ssures between bark ridges may be shallow or

deep but are consistently dark grey in color.

Silvery or light grey, rarely darker. Fissures

between bark ridges moderate to shallow in depth

and often tan to pinkish-tan in color.

Leaf senescence

Leaves yellow and brown by early-mid autumn,

falling in early to mid autumn.

Leaves often green until late autumn, falling in late

autumn or may freeze green on the tree.

Catkins 2 – 4¾ inches in length at peak pollen shed. 5 – 10 inches in length at peak pollen shed.

Nut clusters

One or two nuts per terminal in most clusters,

sometimes 3 – 5, rarely more.

Usually 3 to 5 per cluster, sometimes as many as 7.

in the cases where they are more than half butternut. For

example, a buart “backcrossed” to a butternut results in

seedlings that are ¾ butternut and ¼ Japanese walnut.

Genetic testing with DNA-ngerprinting techniques may

be the only way to reliably identify and untangle the

pedigree of some of these complex hybrid trees (Ross-

Davis et al., 2008; Hoban et al., 2008; Woeste et. al.,

2009). Butternuts do not hybridize with black walnuts

but may hybridize with other walnut species in addition

to Japanese walnut. These hybrids are very rare and not

very fruitful and will not be covered in this publication.

Hybrids are not necessarily undesirable, but we still

know very little about how they will perform as possible

replacements for butternuts, so careful identication is

warranted if you wish to propagate and manage native

butternuts.

No single trait distinguishes a butternut from a hybrid,

but hybrids may be recognized using multiple charac-

teristics (Table 1) and by using the key found in Table

2 (Ross-Davis et al., 2008). Tree growth rate, age, and

other factors can cause variation in the appearance of the

identifying characteristics listed, so use as many of the

traits as possible. Before using the key, the rst thing to

consider is where the tree is growing. Trees in a natural

forest, or at least 300 feet inside a woodlot where there

are no signs of old home sites, orchards, or outbuildings,

are much more likely to be pure butternuts. Hybrids were

typically planted around farms, parks, and yards, and

may naturally regenerate in nearby forest edges. Any

“butternut” in a location where it may have been planted

or naturalized as offspring from a planted tree may be a

hybrid. Another consideration is the health and vigor of

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

the tree. Hybrids tend to resist butternut canker infection,

or heal quickly when infected, and have a rapid growth

rate due to hybrid vigor. Pure butternuts may also grow

vigorously, but most native butternuts are infected with

the butternut canker disease, resulting in obvious cankers

on branches and trunks, decreased growth rate and tree

vigor, and shortened life span. Rarely, a butternut will es-

cape butternut canker disease because it is isolated from,

or possesses some resistance to the disease, so consider

additional identifying traits before making an identica-

tion decision based on tree health or location. Healthy,

pure butternuts exist and are important for future breed-

ing efforts.

Table 2. Key for separating butternuts from hybrids using eld characteristics. To use this key, examine

each specimen for at least ve of the traits listed below. For each trait, assign the specimen a score of 0,

1, or 2. Sum the scores for each of the traits you use, if the total score for your sample is 3 or less, your

sample is probably a butternut. If it is greater than 3, it is probably a hybrid or a heartnut. This key is

intended as a eld guide and is not denitive. In some cases, only genetic testing can separate butternuts

and hybrid trees.

TRAIT 1 Leaf Retention — Figures 11, 12 SCORE

Leaves drop early in the fall, at about the same time as black walnut.....................…………………….……..0

Leaves stay green longer than black walnut but begin dropping before frost........................…………………...1

Leaves stay green late into the fall and drop after a frost.......................…………………………………….…..2

TRAIT 2 Dormant Terminal Bud — Figures 22,23

Terminal bud elongated and slender, conical, and tan colored.......................……………………..…………..0

Terminal bud broadest at base, less elongated, slightly green colored.................……......................….……1

Terminal bud stout, pyramid shaped, green or yellow green in color.....................………………………...….2

TRAIT 3 Dormant Twigs — Figures 2, 22, 23

Dark olive green or reddish-brown, slender, sometimes with hairs below the terminal bud............................0

Tan to brownish green and stout, sometimes with patches of hairs, especially below terminal bud................1

Tan to light green, stout, often with abundant rusty red or tan hairs.................................................................2

TRAIT 4 Lenticel Shape on New Twigs — Figures 2C and 2D, 22, 23

Lenticels on most recent growth uniformly small, round, white, abundant, and evenly distributed;

if some are elongated or dash-shaped, elongation is perpendicular to direction of the branch.......................0

Lenticels on most recent growth mostly small, round, white, abundant, with patchy distribution;

if some are elongated or dash-shaped, elongation is parallel to direction of branch..................................….1

Lenticels on most recent growth large, tan and corky, patchy distribution, many dash-shaped and elongated

parallel to branch....................….....................................................................................................................2

TRAIT 5 Pith Color of 1-Year Twig — Figure 2A

Very dark, chocolate brown.........................................................................................................................…..0

Medium brown (color of dark maple syrup).............................................................................................…..1

Tan to honey colored............................................................................................…………………………......2

TRAIT 6 Leaf Scar — Figure 2

Top edge of most leaf scars straight or slightly arched..................................................................................….0

Top edge of some leaf scars with small descending “V” shaped notch.............................................................1

Top edge of most or all leaf scars with clear descending “V” shaped notch.................................................….2

Figure 12. Hybrid

butternut trees may

retain green foliage until

a killing frost, while pure

butternuts have dropped

all leaves two or more

weeks earlier.

Photo: Lenny Farlee,

HTIRC, Purdue University

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

TRAIT 7 Leaf Length — Figure 10

Most leaves less than 18 inches long..............................................................................................................….0

Many leaves 18 inches or longer......................................................................................................................1

TRAIT 8 Color of Bark Fissures on Mature Trees — Figures 4, 6

Dark grey or black.............................................................................................................................................0

Light grey or silvery...................................................................................................................................…...1

Tan or slightly pinkish.................................................................................................................................…..2

TRAIT 9 Green Hull Characteristics

Densely hairy and very sticky.......................……………………………………………………...............…..0

Somewhat hairy and only slightly sticky....................................................................................................…...2

TRAIT 10 Nut Shape — Figures 13–21

Nut cylindrical, round in cross section, with thin, sharp corrugations. The suture/seam is not

easily distinguished from the longitudinal ridges………………….…...........................................................0

Nut slightly asymmetrical, with noticeable valleys between longitudinal ridges.……………..…..................1

Nut asymmetric, diamond shaped or attened, with dull or sparse corrugations, the suture/seam is easily

identied and forms the widest part of the body of the nut.............................................................................2

TRAIT 11 Catkin Length When Fully Extended and Shedding Pollen

Shorter than 4.5 inches...........................................................................................................................0

4.5 – 5.5 inches...................................................................................................................................…...1

Longer than 5.5 inches...............……………….....................................................................................…..2

Evaluate your tree and sum its score for any 5 of the traits listed above. If your score is:

Zero – 3...........………...Butternut

Greater than 3………...Hybrid or Japanese walnut (heartnut)

Table 2. Continued

Figure 13. Variations in butternut size and appearance (A).

Looking at the end of the nut, a butternut appears round in

cross-section and the sharp, thin corrugations ll the zones

between ridges and suture. The nut suture is not easily

distinguished until it begins to open (B).

Photo: Lenny Farlee, HTIRC, Purdue University

While the shapes and sizes of the nut shells of but-

ternuts vary considerably from tree to tree and across its

native range (Fig. 13A), some characteristics are fairly

consistent and can be valuable for differentiating native

butternuts from hybrids. Native butternuts tend to be

round in cross-section (Fig. 13B), while hybrid nuts tend

to be asymmetrical, angular, or slightly attened (Fig.

14-18). The shell of a butternut has extremely thin, sharp

corrugations extending outward, similar to the cooling

ns on a radiator. In pure butternuts, these corrugations

tend to be evenly distributed between, and reach about

the same height as, the longitudinal ridges and sutures on

the shell (Fig. 13, 19). In contrast, hybrids tend to have

thick or blunt corrugations that are unevenly or sparsely

distributed between the longitudinal ridges creating the

appearance of “valleys” between the ridges (Fig. 15-18,

20, 21). Some hybrid nuts, F1 buarts in particular, have

irregular bumpy surfaces, with no corrugations or ridges.

The suture or seam where a butternut splits open during

germination is generally the same height as the ridges

(Fig. 13). The seam on a hybrid nut may are out away

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

Figure 14. Japanese walnut or heartnut (left, top and

bottom) and butternut (right, top and bottom) easily

hybridize to create butternut hybrids which often

demonstrate physical characteristics intermediate between

the parent trees. Note the prominent suture on Japanese

walnut and the inconspicuous suture resembling the

longitudinal ridges on the butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 15. Hybrid butternut (left, top and bottom) and

butternut (right, top and bottom) showing the prominent

suture and blunt, less abundant corrugations on the hybrid

nut as compared to the butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 16. Hybrid butternut (left, top and bottom) and

butternut (right, top and bottom) showing the prominent

suture, more angular shape and blunt corrugations on the

hybrid nut as compared to butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 17. The differences between the hybrid butternut

(left, top and bottom) and the butternut (right, top and

bottom) are less pronounced, but still present including:

prominent suture, blunt corrugations and ridges, and a

more angular appearance of the hybrid nut as compared to

the butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

from the body of the nut, creating a triangular, attened

appearance at the tip of the nut (Fig. 15-17).

Hybrids can become very difcult to separate from

pure butternuts, particularly when they become more

genetically mixed with native butternuts. Combining

information about the location of the tree, history of the

area, physical characteristics, vigor and health of the tree,

and appearance of the nuts will help you determine if you

have a hybrid or pure butternut.

This publication is an adaptation and expansion of

an article that appeared in the Northern Journal of

Applied Forestry: Woeste, K.E., L. Farlee, M.E.

Ostry, J.R. McKenna, and S. Weeks. 2009. A Forest

Manager’s Guide to Butternut. Northern Journal of

Applied Forestry. 26(1): 9-14.

Figure 18. This suspected back-cross hybrid butternut

(left, top and bottom) very closely resembles pure butternut

(right, top and bottom). Some subtle differences can still

be seen in the more angular appearance of the nut and

the “valleys” between the ridges where corrugations are

shorter and sparser than in pure butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 19. Long, sharp

corrugations located on

and between the ridges of a

native butternut.

Figure 20. Short, mostly

blunt corrugations on and

between ridges of a hybrid

butternut.

Figure 21. Sparse, blunt

corrugations on and

between ridges of a hybrid

butternut (buart).

All photos: Lenny Farlee,

HTIRC, Purdue University

Figure 22. Elongated lenticels, stout twig, notched leaf

scar, and large pyramidal terminal bud typical of hybrid

butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Figure 23. Small, round lenticels, slender twig, arched or

at-topped leaf scar, and slender, elongated tan terminal

bud typical of pure butternut.

Photo: Lenny Farlee, HTIRC, Purdue University

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

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28; Lafayette, IN. Gen. Tech. Rep. NC-243. St. Paul,

MN: USDA, Forest Service, North Central Research

Station.

Rink, George. 1990.

Juglans cinerea

L. Butternut

386-390 in

Silvics of North America

, Burns, R.M.,

and B.H. Honkala (tech. coords.). USDA For. Serv.,

Washington, D.C.

Ross-Davis, A.; Huang, A. Z.; McKenna, J.R.; Ostry,

M.E.; and Woeste, K.E. 2008. Morphological and

molecular methods to identify butternut (

Juglans

cinerea

L.) and butternut hybrids: Relevance to

butternut conservation. Tree Physiology 28:1127-1133.

USDA, ARS National Genetic Resources Program.

Germplasm Resources Information Network-(GRIN)

[Online Database]. National Germplasm Resources

Laboratory, Beltsville, MD. URL. Available online

at www.ars-grin.gov/cgi-bin/npgs/html/index.pl; last

accessed Nov. 13, 2007.

Waugh, F.W. 1916.

Iroquois Foods and Food

Preparation

. Geol. Sur. Can. Mem. 86 (Anthropol.

Ser. 12). Dept. of Mines, Ottwawa, Canada. 235 p.

Woeste, K.E., Farlee L., Ostry, M.E., McKenna, J.R.,

and S. Weeks. 2009. A Forest Manager’s Guide to

Butternut. Northern Journal of Applied Forestry.

26(1):9-14.

Identiﬁcation of Butternuts and Butternut Hybrids • FNR-420-W

Additional Resources

Detailed information on the life-history, range, identi-

cation and a variety of other characteristics of butternut

is readily available in printed and digital format.

Several research and management documents for

butternut are accessible from the USDA Forest Service

Northern Research Station: http://

nrs.fs.fed.us/

• The USDA Forest Service Conservation Assessment

for butternut is available at

www.fs.fed.us/r9/

wildlife/tes/ca-overview/docs/plant_juglans_cinera-

Butternut2003.pdf

• The Fire Effects Information System (FEIS) provides

an index of information for butternut at

www.fs.fed.

us/database/feis/plants/tree/jugcin/all.html

• The USDA NRCS PLANTS Database also provides a

butternut plant prole at

http://plants.usda.gov/

• The biological characteristics (silvics) of butternut

can be found at

www.na.fs.fed.us/spfo/pubs/silvics_

manual/Volume_2/juglans/cinerea.htm

• ConservationandManagementofButternuts,

FNR-421-W, provides recommendations for retention,

management and propagation of butternuts.

In addition to these information sources, many states within

the range of butternuts will have information available

through forestry, conservation, and botanical survey

organizations.

7/10

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Purdue University is an Afﬁrmative Action institution. This material may be available in alternative formats.

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Order or download materials at the Purdue Extension

Education Store • www.the-education-store.com

Contact Information for Foresters

Indiana Division of Forestry

402 West Washington Street, Rm 296W

Indianapolis, IN 46204

(317) 232-4105

www.in.gov/dnr/forestry/

Directory of Professional Foresters:

Indiana Forestry & Woodland Owners Assoc.

1011 North 725 West

West Lafayette, IN 47906

www.ndindianaforester.org

Purdue Extension Foresters

(765) 494-3583

www.fnr.purdue.edu/

Acknowledgements

The authors wish to thank Brian Beheler and Phil

O’Connor for their very helpful expert review of this

document.