Juglans cinerea

Juglandaceae -- Walnut family

    George Rink

    Butternut (Juglans cinerea), also called white walnut or  oilnut, grows rapidly on well-drained soils of hillsides and  streambanks in mixed hardwood forests. This small to medium-sized  tree is short lived, seldom reaching the age of 75. Butternut is  more valued for its nuts than for lumber. The soft coarse-grained  wood works, stains, and finishes well. Small amounts are used for  cabinetwork, furniture, and novelties. The sweet nuts are prized  as a food by man and animals. Butternut is easily grown but must  be transplanted early because of the quickly developing root  system.

General: Walnut family (Juglandaceae). Small to medium-sized native trees with stiff upright branches and a wide-spreading crown, the young twigs, stems, and leaflets have hairs sticky-oily to the touch; terminal buds 12-18 mm long; bark brownish-gray, thick, shallowly divided into smooth or scaly plates. Leaves are pinnately compound, the leaflets (7-) 11-17, ovate to lanceolate or oblong-lanceolate, ± symmetric, mostly 5-11cm long, with finely toothed margins, terminal leaflet present, the lower surfaces densely covered with stellate hairs. Flowers are unisexual, female (pistillate) and male (staminate), but on the same tree (the species monoecious), usually not opening simultaneously on any individual tree; male flowers in slender catkins 6-14 cm long, the female flowers in terminal clusters of 6-8 flowers each. Fruit is an oblong-ovoid nut 4-6(-8) cm long, single or in clusters of 2-5, with a hard, thick, deeply furrowed shell enclosed by a thick husk with a sticky-glandular surface. The nuts usually remain on the tree until after leaf fall. The common name refers to the mature nut kernels, which are sweet and oily, like butter.

More info for the terms: frequency, tree

Butternut is distributed from southeastern New Brunswick throughout the
New England States except for northern Maine and Cape Cod. Its range
extends south to include northern New Jersey, western Maryland,
Virginia, and Tennessee. Small isolated pockets occur in North
Carolina, northwestern South Carolina, northern Georgia, northern
Alabama, northern Mississippi, and Arkansas. Westward it is found in
eastern Iowa and southeastern Minnesota. Disjunct populations occur in
Wisconsin, Michigan, and northeast into Ontario and Quebec. Throughout
most of its range, butternut is not a common tree and its frequency is
declining. The ranges of butternut and black walnut overlap, but
butternut occurs farther north than and not as far south as black walnut
[3,26,30].

Butternut is cultivated in Hawaii [33].

AL AR CT DE GA HI IA IL IN KY
MA MD ME MI MN MO MS NC NH NJ
NY OH PA RI SC TN VA VT WI WV
NB ON PQ

Butternut is found from southeastern New Brunswick throughout the  New England States except for northwest Maine and Cape Cod. The  range extends south to include northern New Jersey, western  Maryland, Virginia, North Carolina, northwestern South Carolina,  northern Georgia, northern Alabama, northern Mississippi, and  Arkansas. Westward it is found to central Iowa and central  Minnesota. It grows in Wisconsin, Michigan, and northeast into  Ontario and Quebec. Through most of its range butternut is not a  common tree, and its frequency is declining (4). The ranges of  butternut and black walnut (Juglans nigra) overlap, but  butternut occurs farther north and not as far south as black  walnut.

   
  -The native range of butternut.

Wallia cinerea (L.) Alef.:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Juglans cinerea L.:
Canada (North America)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

N.B., Ont., Que.; Ala., Ark., Conn., Del., Ga., Ill., Ind., Iowa, Ky., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Juglans cinerea occurs throughout the central and eastern United States and southeastern Canada (Fernald 1950, Smith 1988, Brown and Kirkman 1990, Gleason and Cronquist 1991, TNC HO 1992).

Butternut is primarily a species of the northeastern and north-central US and southern Canada from southeastern New Brunswick to Ontario and Quebec; in the US in Minnesota to Missouri and eastward through Tennessee into North Carolina and Virginia, with disjunct outlyers in Arkansas, Mississippi, Alabama, South Carolina, and Georgia. It is uncommon throughout most of its range and formally listed as rare in many of the states in which it occurs. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

More info for the term: tree

Butternut is a small to medium-sized tree averaging 40 to 60 feet (12-18
m) in height and 12 to 24 inches (30-60 cm) in d.b.h. This tree has a
short trunk which is divided into a few ascending limbs with large
spreading, sparsely forked branches. The smaller branches tend to bend
downwards and then turn up at the ends. The crown is open, broad,
irregular in outline and rounded at the top. The root system is
composed of a number of wide-spreading laterals that grow to a
considerable depth. Usually a taproot develops in deep soils [7,21,24].
Butternut grows fast, especially as a seedling, but usually does not
live longer than 75 years [5,21,24].

Trees , to 20(-30) m. Bark light gray or gray-brown, shallowly divided into smooth or scaly plates. Twigs with distal edge of leaf scar straight or nearly so, bordered by well-defined, tan-gray, velvety ridge; pith dark brown. Terminal buds conic, flattened, 12-18 mm. Leaves 30-60 cm; petiole 3.5-12 cm. Leaflets (7-)11-17, ovate to lanceolate or oblong-lanceolate, ± symmetric, (2.5-)5-11(-17.5) × 1.5-6.5 cm, margins serrate, apex acuminate; surfaces abaxially with abundant 4-8-rayed fasciculate hairs, scales, and sometimes capitate-glandular hairs, axils of proximal veins with prominent tufts of fasciculate hairs, adaxially with scattered fasciculate hairs or becoming glabrescent; terminal leaflet present, usually large. Staminate catkins 6-14 cm; stamens 7-15 per flower; pollen sacs 0.8-1.2 mm. Fruits 3-5, ellipsoid to ovoid or cylindric, 4-8 cm, smooth, with dense capitate-glandular hairs; nuts ellipsoid to subcylindric or ovoid, 3-6 cm, surface with ca. 8 high, narrow, longitudinal main ridges, with narrow, interrupted, longitudinal ridges or lamellae between main ridges.

There are some pubescence differences which will help to distinguish Butternut from the Black Walnut, even when the distinctive dark pith is not exposed. In J. cinerea, there is often a pad of dense small hairs extending transversely along the upper margin of the old leaf scars; in J. nigra, this pad is absent, although the circular area of bud pubescence is confusing, and some specimens are ambiguous. The underside of the leaflets in J. cinerea is +/- densely covered with mostly stellate hairs, while in J. nigra the pubescence is sparser and mostly of simple hairs. The pubescence of cinerea, including that on the fruit, is more clammy than that of J. nigra. Persons familiar with the species in the field will also know differences in fragrance of the foliage and fruit and in stain from the husks--all difficult to expresss in words (Voss, 1980).

Wallia cinerea (Linnaeus) Alefeld

More info for the term: cover

Butternut is found most frequently in coves, on stream benches and
terraces, on slopes, in the tallus of rock ledges, and on other sites
with good drainage [20,28]. It is found up to an elevation of 4,900
feet (1,500 m) in the Virginias [27,31]. In addition to those indicated
in the SAF cover type slot (Distribution and occurence), common tree
associates include black walnut (Juglans nigra), hickory (Carya spp.),
and white ash (Fraxinus americana) [1,3,20,21,24,27].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

14 Northern pin oak
20 White pine - northern red oak - red maple
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
26 Sugar maple - basswood
27 Sugar maple
28 Black cherry - maple
30 Red spruce - yellow birch
31 Red spruce - sugar maple - beech
32 Red spruce
33 Red spruce - balsam fir
34 Red spruce - Fraser fir
42 Bur oak
43 Bear oak
44 Chestnut oak
45 Pitch pine
46 Eastern redcedar
50 Black locust
51 White pine - chestnut oak
52 White oak - black oak - northern red oak
53 White oak
55 Northern red oak
57 Yellow poplar
59 Yellow poplar - white oak - northern red oak
60 Beech - sugar maple
62 Silver maple - American elm
108 Red maple
109 Hawthorn

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southereastern spruce - fir forest
K099 Maple - basswood forest
K100 Oak - hickory
K101 Elm - ash forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods - fir forest
K108 Northern hardwoods - spruce forest
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES10 White - red - jack pine
FRES11 Spruce - fir
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES15 Oak - hickory
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch

Butternut grows best on streambank sites and on well-drained  soils; it is seldom found on dry, compact, or infertile soils. It  grows better than black walnut, however, on dry, rocky soils,  especially those of limestone origin.

    Butternut is found most frequently in coves, on stream benches and  terraces, on slopes, in the talus of rock ledges, and on other  sites with good drainage, primarily on soils of the orders  Alfisols and Entisols. It is found up to an elevation of 1500 in  (4,900 ft) in the Virginias, at much higher altitudes than black  walnut (4,18).

Climatic conditions within the botanical range of butternut vary  widely. Mean annual temperature ranges from 16° C (60°  F) in Alabama to 4° C (40° F) in New Brunswick, with an  average maximum of 41° C (105° F) and minimum of -34°  C (-30° F). Annual precipitation ranges from 630 mm (25 in)  in southeastern Minnesota to 2030 mm (80 in) in the southern  Appalachians. The frost-free period is 210 days in the southern  part of the range and 105 days in the northern part (6).

    Butternut is generally considered to be more winter-hardy than  black walnut.

Rich woods of river terraces and valleys, also dry rocky slopes; of conservation concern; 0-1000m.

Comments: Juglans cineara typically grows in rich mesophytic forests, lower slopes, ravines, and various types of bottomland, including banks and terraces of creeks and streams, and floodplain forests (Fernald 1950, Gleason and Cronquist 1991). This species achieves its best growth in well-drained bottomland and floodplain soils.

The following provides additional information on the specific habitats of J. cinerea in several states from different parts of the species' range:

The habitat in Ohio is mesic river terraces and ravines (Cusick 1992).

Michigan habitat includes streambanks, swamp forests, and upland beech-sugar maple, oak-hickory, and mixed hardwood stands (Voss 1985). In southern Michigan sites, associates may include such species as Ulmus americana (American elm), Acer saccharinum (silver maple), Fraxinus quadrangulata (blue ash), Betula alleghaniensis (yellow birch), Tilia americana (basswood), and many woodland and swamp herbs. In some areas, butternut occurs occasionally as a roadside tree.

The habitat in Illinois and Wisconsin is mesic and riparian hardwood forests, where associates of the overstory include Acer saccharum (sugar maple), Carpinus caroliniana (blue beech), Celtis occidentalis (hackberry), Fagus grandifolia (American beech), Prunus serotina (black cherry), Quercus alba (white oak), Quercus macrocarpa (bur oak), Quercus rubra (red oak), Tilia americana (basswood), and Ulmus americana (American elm). The herbaceous associates of this habitat include Claytonia virginiana (spring beauty), Dicentra cucullaria (squirrel corn), Hydrophyllum appendiculatum (appendaged waterleaf), Isopyrum biternatum (false meadow-rue), and Solidago caesia (woodland goldenrod). In wooded floodplain habitats, associate plant species include Celtis occidentalis, Cryptotaenia canadensis (honewort), Elymus virginicus (Virginia rye grass), Fraxinus pennsylvanica (red ash), Galium aparine (cleavers), Geum canadense (geum), Hydrophyllum virginianum (Virginia waterleaf), Laportea canadensis (wood nettle), Ranunculus septentrionalis (swamp buttercup), Toxicodendron radicans (poison ivy), Rudbeckia laciniata (cutleaf coneflower), Ulmus americana, and Viola sororia (woolly blue violet). A characteristic habitat in the Chicago region is springy, wooded, calcareous slopes, where limey water percolates through gravelly soils. Associate plant species in this habitat may include Angelica atropurpurea (angelica), Caltha palustris (marsh marigold), Cardamine bulbosa (spring cress), Fraxinus nigra (black ash), Lilium michiganense (Michigan lily), Mitella diphylla (bishop's cap), Ribes americanum (swamp gooseberry), Smilacina stellata (starry false solomon's seal), Solidago patula (swamp goldenrod), and Symplocarpus foetidus (skunk cabbage) (Swink and Wilhelm 1979).

The habitat in Indiana is mesic forests (Homoya 1992).

The typical habitat in Kentucky is mesic wooded ravines along streams, mesic limestone gorges, mesic deciduous forest, second growth in mixed hemlock forest, and upland mesic woods, occurring with Fraxinus americana (white ash), and several other species (KY HP 1992).

In Tennessee, Juglans cinerea occurs along creek bottoms in mesic forests and on lower slopes (TN ESD 1992).

In Mississippi, this species occurs on calcareous bluffs, along river and stream drainages, in mesophytic forests, and calcareous ravines. Populations are often found on north-facing slopes. Associate plant species include Acer spp. (maple), Carya spp. (hickory), Juglans nigra (black walnut), Liriodendron tulipifera (tuliptree), and Quercus macrocarpa (bur oak) (MS NHP 1992).

Habitat in Delaware consists of northwest-facing slopes of pastures, banks of streams running through meadows, and floodplain woods with partial shade (DE NHP 1992).

In Massachusettes this species a generalist in terms of soil moisture (it's found along a continuum from river bottomlands to mesic forests to talus and dry balds) but it does not seem to be a generalist in terms of bedrock substrate-in MA it avoids acid, nutrient poor substrates and appears to be restricted to areas underlain by basalt, marble, or dolomite (M. Dow Cullina, pers. comm., 2006).

Adaptation: Butternut is found most frequently in rich woods of coves and stream benches and terraces, on slopes, in the talus of rock ledges, and on other sites with good drainage; at elevations of 0-1000 (-1500) meters. Young trees may grow in considerable competition, but they are shade-intolerant and mature trees must reach the overstory. Flowering occurs from April-June and fruiting from September-October.

General: Seed production begins at about 20 years and is optimum from 30-60 years. Good crops can be expected every 2-3 years, with light crops during intervening years. Premature seed losses may result from consumption by insects, birds, and rodents, and a lack of butternut trees in the immediate vicinity may limit pollination and fruit formation. Seeds germinate in the spring after seedfall and a cold period at 20°-30° C. for 90-120 days to break dormancy.

Stumps of young butternut trees and saplings are capable of sprouting. The trees are reported to be slow growing and seldom live longer than 75 years.

Butternut is found with many other tree species in several  hardwood types in the mixed mesophytic forest. It is an  associated species in the following four northern and central  forest cover types (5): Sugar Maple-Basswood (Society of American  Foresters Type 26); Yellow-Poplar-White Oak-Northern Red Oak  (Type 59); Beech-Sugar Maple (Type 60); and River Birch-Sycamore  (Type 56). Commonly associated trees include basswood (Tilia  spp.), black cherry (Prunus serotina), beech (Fagus  grandifolia), black walnut (Juglans nigra), elm (Ulmus  spp.), hemlock (Tsuga canadensis), hickory (Carya  spp.), Oak (Quercus spp.), red maple (Acer  rubrum), sugar maple (A. saccharum), yellow-poplar  (Liriodendron tulipifera), white ash (Fraxinus  americana), and yellow birch (Betula alleghaniensis).  In the northeast part of its range, it is often found with  sweet birch (Betula lenta) and in the northern part of  its range it is occasionally found with white pine (Pinus  strobus) (4,15). Forest stands seldom contain more than an  occasional butternut tree, although in local areas it may be  abundant. In the past, West Virginia, Wisconsin, Indiana, and  Tennessee have been the leading producers of butternut timber.

Insect enemies of butternut are often  pests of associated trees as well. Some insects commonly found on  butternut include wood borers, defoliators, nut weevils,  lacebugs, husk flies, and bark beetles. The most serious insect  pest at this time is the butternut curculio (Conotrachelus  juglandis), which injures young stems and fruit (8,21).

    The most serious disease of Juglans cinerea is butternut  decline or butternut canker. In the past the causal organism of  this disease was thought to be a fungus, Melanconis  juglandis; but now this fungus has been associated with  secondary infections and the primary causal organism of the  disease has been identified as another species of fungus, Sirococcus  clavigignenti-juglandacearum. Symptoms of the disease include  dying branches and stems. Initially, cankers develop on branches  in the lower crown. Spores developing on these dying branches are  spread by rainwater to tree stems. Stem cankers develop 1-3 years  after branches die. Tree tops killed by stem-girdling cankers do  not resprout (19,20). Diseased trees usually die within several  years (11,16). The disease is reported to have eliminated  butternut from North and South Carolina (1). The disease is also  reported to be spreading rapidly in Wisconsin; between 1978 and  1983 the incidence of butternut canker in a young, isolated  plantation increased exponentially from 5 percent in 1976 to 76  percent in 1983 (20). By contrast, black walnut seems to be  resistant to the disease.

    Bunch disease also attacks butternut. Currently, the causal agent  is thought to be a mycoplasmalike organism. Symptoms include a  yellow witches'broom resulting from sprouting and growth of  axillary buds that would normally remain dormant. Infected  branches fail to become dormant in the fall and are killed by  frost; highly susceptible trees may eventually be killed.  Butternut seems to be more susceptible to this disease than black  walnut (2,17).

    The common grackle has been reported to destroy immature fruit and  may be considered a butternut pest when populations are high  (14).

    Butternut is very susceptible to fire damage, and although the  species is generally windfirm, it is subject to frequent storm  damage (4).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: Thousands of occurrences across a wide range.

More info for the term: hardwood

Butternut grows well in mixed hardwood forests that have been protected
from fire [22]. A single hot fire or repeated cool fires can
effectively eliminate butternut in mixed hardwood stands [32].

More info for the term: root crown

Butternut is very susceptible to fire. Aboveground portions are easily
killed by fire, and sprouting from the root crown or stump is rare
[24,32].

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Although young trees can tolerate partial shade, butternut must be in
the overstory to thrive and is classified as intolerant to shade and
competition [11]. Like other members of the Junglandaceae family,
butternut produces a substance called juglone, a naphthoquinone that is
selectively toxic to associated vegetation. Greatest concentrations of
juglone are in root tissue and fruit husks, with lesser amounts in the
leaves, catkins, buds, and inner bark [24].

More info for the term: natural

Seed production and dispersal: Commercial seed-bearing age begins at 20
years and is optimum from 30 to 60 years. Good crops of seed can be
expected every 2 to 3 years. A high percentage of seeds are sound, but
high seed losses occur due to consumption by birds, insects, and
rodents. Natural pollination failures often occur due to the lack of
pollinated trees in immediate vicinity [4,24]. Upon ripening, seeds are
dispersed by gravity, squirrels, and other rodents. [9,24].

Vegetative propagation: Stumps of young butternut trees and saplings
can sprout [4,32].

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More info for the term: phanerophyte

Mesophanerophyte
Microphanerophyte

More info for the term: tree

Tree

Butternut does not typically survive fires that destroy aboveground
plant parts [24].

survivor species; on-site surviving deep underground stems
off-site colonizer; seed carried by animals or water; postfire yr 1&2

Butternut does not typically sprout after fire [22,24,32].

Although young trees may  withstand competition from the side, butternut does not survive  under shade from above. It must be in the overstory to thrive  and, therefore, is classed as intolerant of shade and  competition.

    Like other members of the Juglandaceae family, butternut produces  a substance called juglone, a naphthoquinone that is selectively  toxic to associated vegetation. Greatest concentrations of  juglone are in root tissue and fruit husks with lesser amounts in  leaves, catkins, buds, and inner bark (12,13).

    Within its optimum range and on good sites, butternut is usually  considered a desirable component of forest stands; it has been  classed as a "less desirable" tree in southern  Appalachian coves (4).

On favorable sites the root system is deep,  but it also may be widespreading.

Juglans cinerea achieves optimal growth on well-drained soils of bottomlands and floodplains, but rarely occurs in pure stands. According to Rink (1990), this species grows best in riparian sites and well-drained soils, but is seldom found on dry, compact, or infertile soils. Rink also notes that butternut is found at much higher elevations (up to 4900 ft) in the Virginias than black walnut. Butternut is shade-intolerant, growing best in full sunlight. Young trees can tolerate some competition from the side, but will not withstand shade from above. This species needs to be in the canopy in order to survive. Reproduction is successful only in areas where shade does not inhibit its growth, such as stand openings or in fields (Skilling 1993, Ostry et al. 1994).

This species is being seriously impacted, if not devastated, by a canker fungus (Sirococcus clavigignenti-juglandacearum) that is spreading rapidly throughout its range, and few stands remain uninfected. The origin of the disease is unknown, although Fogelson and Campbell (1990) believe it may have been introduced about 40 years ago on the east coast of the United States. According to Anderson (1993), 40- year-old cankers have been observed in North Carolina. Long noted as suffering from a canker dieback (frequently called "butternut decline"), scientists from Wisconsin first identified the disease agent as a new species of Sirococcus in 1967, although tests of trees in North Carolina demonstrated its presence there in 1952. This disease has spread quickly (within 30 years) throughout butternut's range, infecting and killing trees in all locations. In the Great Lakes states, all sites examined by researchers had been infected with canker. The disease vectors are poorly known, but the canker is believed to be transmitted at least in part by raindrops splashing spores from infected trees onto healthy ones, and possibly via insects. If the spores become airborne, they are able to be dispersed over great distances. The spores are produced throughout the growing season and can survive when weather conditions are cool and skies are overcast. (Kuntz et al. 1979, Fogelson and Campbell 1990, Forest Service News 1992, Ostry et al. 1994).

Symptoms of the disease include the appearance of lens-shaped cankers on the trunk, limbs, twigs, and immature nut of the tree. In spring, an inky-black, thin fluid is exuded from the cankers. These cankers usually continue to grow in size and girdle the tree, eventually killing it by destroying the cambium. The girdling of the tree often causes a wilting of the leaves, especially noticeable in the crown (Fogelson and Campbell 1990). Trees with reduced vigor become susceptible to insects and secondary disease agents, particularly Melanconis juglandis (E. and E.) Graves, which causes branch dieback (Skilling 1993).

Butternut is an important source of mast for wildlife, especially in the northern part of its range, where black walnut (Juglans nigra) does not occur. Squirrels and other rodents are some of the consumers of the seeds. (Ostry et al. 1994).

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More info for the term: tree

Butternut flowers from April to June, depending on location. The fruit
matures in September and October and usually remains on the tree until
after leaf fall [4,12].

Flowering spring (Apr-Jun).

Stumps of young butternut trees  and saplings are capable of sprouting. Also, butternut can be  propagated by grafting, although the techniques have not yet been  perfected. Various degrees of success have been demonstrated with  intra-specific as well as inter-specific grafting in the genus  (9).

Seeds of butternut usually  germinate in the spring following seedfall.

    Germination is hypogeal. Seedlings develop a taproot on all sites  except the most shallow soils, but the taproot is much less  pronounced than on black walnut. In general, butternut seedlings  have more fibrous root systems than black walnut.

Commercial seed-bearing  age begins at about 20 years and is optimum from age 30 to 60  years. Good crops can be expected every 2 to 3 years, with light  crops during intervening years. Thrifty trees may yield 9 to 35  liters (0.25 to 1 bushel) of cleaned seeds. A high percentage of  mature seeds are sound, but high premature seed losses in  butternut have been reported. Possible causes include consumption  by insects, birds, and rodents as well as natural pollination  failures due to a lack of pollinating trees in the immediate  vicinity (4,10,14,21).

    Upon ripening, seeds are dispersed by gravity and by squirrels and  other rodents. At this time, the seeds are dormant. Cold  stratification for 90 to 120 days at temperatures of 20° to  30° C (68° to 86° F) overcomes dormancy.

Butternut flowers from April to  June, depending upon location. The species is monoecious; male  flowers are slender catkins that develop from axillary buds and  female flowers are short terminal spikes home on current year's  shoots. Flowers of both sexes do not usually mature  simultaneously on any individual tree (3).

    The fruit is an oblong-ovoid pointed nut, 3.8 to 5.5 cm (1.5 to  2.2 in) long, that matures in September and October of the year  of pollination. Nuts occur singly or in clusters of from 2 to 5.  The kernel or seed of the nut is sweet, oily, and edible. The nut  is enclosed by an indehiscent husk that contains a glandular  pubescence on the surface. The fruit usually remains on the tree  until after leaf fall (3).

Male and female flowers borne seperately on the same tree. Squirrels, rabbits and white tailed deer eat the nuts. Squirrels disperse them.

Butternut grows fast, especially as a  seedling, although it usually does not live longer than 75 years  and is short lived in relation to its common tree associates.

    Mature trees rarely reach a height of more than 30 m (100 ft) and  a d.b.h. of 91 cm (36 in). Average-sized trees are from 12 to 18  m (40 to 60 ft) in height and 30 to 61 cm (12 to 24 in) in d.b.h.  (4).

Butternut hybridizes with English walnut (Juglans regia L.)  to produce J. x quadrangulata (Carr.) Rehd. It  also crosses with Japanese walnut J. ailantifolia Carr.  to produce J. x bixbyi Rehd. Butternut is also  reported to successfully hybridize with little walnut (J.  microcarpa Berland.) and Manchurian walnut (J.  mandshurica Maxim.) (6,14). Reports of crosses between  butternut and black walnut have not been substantiated. Butternut  is thought to have a haploid chromosome number of 16.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 3
Specimens with Barcodes: 5
Species With Barcodes: 1

Canada

Rounded National Status Rank: N3 - Vulnerable

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Occurs infrequently in forest stands throughout most of the eastern United States and Canada. The abundance and condition are both in rapid decline due to butternut canker disease, with no known remedy. At the time of this review (2006), even with the canker evident and widespread, there are a large number of occurrences persisting and resistant trees, though rare, are found in many areas of the range. The species is not currently vulnerable to extinction, but there is certainly reason for longer-term concern. The rank should be reevaluated frequently.

Environmental Specificity: Moderate to broad.

Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.

Global Short Term Trend: Decline of 10-50%

Comments: Butternut is experiencing a rapid decline due to the spread of butternut canker. The disease has spread rapidly throughout the species' range, and the downward trend is likely to continue until disease resistant trees are identified, propagated, and successfully reintroduced.

Schlarbaum et al. (1997) reported that 77 percent of butternut trees in the southeastern United States died in a 30 year period. Forest Service survey data indicated overall declines of 23% in the number of butternut trees in 7 midwestern states over various time intervals ranging back to 1990 (USDA NRCS 2004).

Global Long Term Trend: Increase of 10-25% to decline of 30%

Degree of Threat: Very high - high

Comments: The major threat to Juglans cinerea throughout its entire range is susceptibility to the butternut canker disease caused by the fungus Sirococcus clavigignenti-juglandacearum. The fungus disrupts nutrient flow through cambium areas, which is generally fatal. It may take trees more than 40 years to die, but in many cases, death has rapidly followed infection. Following dieback, this species does not leave live rootsprouts and usually does not leave viable seed. The wood, which is highly prized for cabinet-making and other types of woodworking, is in great demand. "Pre-emptive salvage" cutting, in which any remaining healthy trees are cut in the attempt to get full value for them before they become diseased, is common (at least in the Great Lakes states). The salvage of non-infected trees, however reduces the pool of potentially disease resistant individuals. Woodlot management is also a a form of threat to this species, since it may not involve providing the types of disturbance (e.g., soil disturbance) needed by this shade-intolerant species to successfully reproduce and establish new individuals. Unless management practices are altered to allow for open, disturbed areas, it is unlikely that there will be significant butternut reproduction (Skilling 1993).

In many areas healthy butternut trees have been found growing adjacent to diseased trees and these presumably resistant trees have remained healthy over a 12 year period (Ostr and Woeste 2004).

Butternut canker disease can be identified by the following characteristics or conditions: (1) trees with dying branches or dead tops, and tufts of shoots (epicormic shoots) below the dead portions; (2) discolored bark that in spring exudes an inky-black, thin fluid from cracks in the cankers, and in summer has sooty bark patches that commonly have a white margin; and (3) cankers of various types. In early stages, cankers are sunken and elongate, originating at leaf scars, buds, and in various tree wounds. In latter stages, cankers are visible on older stem and branch portions, many loosely covered with shredded bark and bordered by successive callus layers. Infected trees are also characterized by dark brown to blackish wood portions in elliptical patterns beneath the bark. Dieback occurs through single or coalescing cankers girdling branches, and branch suckers and stem sprouts quickly become infected and die.

An additional threat is hybridization with Juglans ailantifolia (heartnut), a species from Japan which is marketed as a nut tree (McDaniel 1979).

More info for the term: tree

Within its optimum range and on good sites, butternut is usually
considered a desirable component of forest stands. It has been
classified as a "less desirable tree" in southern Appalachian coves
[1,13,19].

The most serious disease of butternut is butternut decline or butternut
canker. The causal organism of this disease is the fungus Sirococcus
clavigignenti-juglandocearum. Symptoms include dying branches and
stems. Spores develop on these dying branches and are spread by
rainwater to tree stems. Stem cankers develop 1 to 3 years after
branches die. Trees top-killed by stem-girdling cankers do not resprout
[24]. This disease is reported to have almost eliminated butternut from
North and South Carolina [2,18,25].

Restoration Potential: The restoration potential of butternut is uncertain, owing to the rapid spread of butternut canker. Since most remaining trees are infected with the fungal disease, or will likely be infected, recovery may be extremely difficult. Many of the infected trees are expected to die within the next 20 years, although Anderson (1993) notes that there are many trees in North Carolina that have survived 40 years with canker. There is presently no known cure for the annual fungus. However, several apparently resistant butternut trees have been located adjacent to infected trees in Virginia and elsewhere. It may be possible to clone these and other apparently disease-resistant butternut trees to produce shoots that could be reintroduced throughout the species' range. The U.S. Forest Service and several state forestry units are working to locate and test trees that may be resistant to infection. (Fogelson and Campbell 1990, Skilling 1993).

Activities that should be undertaken to help restore butternut populations include: (1) conducting inventories for butternut to assess its health and status; (2) increasing the understanding of the butternut canker disease cycle; (3) developing silvicultural methods that will ensure effective regeneration; (4) beginning a seed collection program along with test seeding and transplanting plans; (5) locating disease-resistant trees within the forest; (6) establishing clone banks and seed orchards by using propagation techniques, including tissue culture; (7) testing the possibility of developing resistant trees by using intraspecific tree breeding techniques; and (8) monitoring the effect of current management being employed where butternut is growing and making beneficial refinements as needed. (Ostry et al. 1994).

Preserve Selection and Design Considerations: There are no known preserve designs that would optimize the conservation of this species due to the rapid rate of infection and spread of butternut canker disease.

Management Requirements: There are no effective or practical management techniques known that would completely protect butternut due to the butternut canker. Some sites are being managed by extracting infected individuals to inhibit the spread of the canker, a treatment Skilling (1993) states has no known value. In addition, the practice of extracting healthy trees from infected stands to salvage the economically valuable wood serves to further reduce the potential pool of resistant germplasm. At present, the best management prescription is to locate and monitor butternut stands so that potentially resistant germplasm strains can be identified. Criteria for identifying candidate trees include the following: (1) the tree must be in a stand already infected with canker where the possibility of exposure is high; (2) the tree must be canker-free, or if cankers are present, must have overgrown them; (3) the tree must be at least 10 inches in diameter at breast height (dbh) to ensure that it has been exposed to canker over a number of years; and (4) the tree(s) must be owned by someone who is willing to let researchers collect scion wood (grafting material) as well as nuts from the tree(s) over a number of years (Ostry et al. 1994).

At least three fungicides have been tested on butternut canker (Anderson 1988). One of those fungicides is benomyl, which has provided some effective treatment at low concentrations. However, this treatment is not practical for treating scattered trees within a forest stand.

Because butternut is a shade-intolerant species, its natural propagation can be assisted by managing forests to create disturbance conditions (e.g., canopy gaps, openings, soil disturbance) needed for colonization and establishment of new individuals. As openings grow closed over time, they should be made larger so that established butternut trees can achieve full growth and development (Ostry et al. 1994).

All occurrences of healthy (non-infected and resistant) trees should be tracked; resistant trees, which are of the greatest importance for conservation of the species, should be most actively sought and identified.

Management Programs: Concern over the fate of butternut has led to moratoriums on harvesting. In Minnesota, the Department of Natural Resources issued a moratorium in 1992 on cutting healthy butternut trees on state lands administered by the Division of Forestry (Rose 1992, Skilling et al. 1993). The moratorium did not prohibit the salvage of diseased trees, but encouraged private landowners to abstain from harvesting healthy trees to maintain an optimal pool of potentially resistant germplasm. The U.S. Forest Service has placed a moratorium on cutting healthy butternut trees in National Forests as of March 1993. Within Region 9 of the U.S. Forest Service, butternut has been placed on the sensitive species list; in Region 8 it has been placed on the sensitive species list in Mississippi, with similar designation recommended for several other National Forests.

Management for butternut within the Great Smoky Mountains National Park consists of gathering fruits from wild populations and either storing them for several years or planting them immediately. Germination of seeds is slow and may take several months, but the process can be hastened by treating seed coats with a weak acid to soften them. Seeds are germinated in soil-filled medium pots. Approximately 100 seedlings have be germinated and transplanted into suitable habitat within the same year using this method. Long-term monitoring of tagged butternut trees has also been initiated within the Park, and studies have found that virtually all butternut trees within the Park are infected (Rock 1992).

Monitoring Programs: Annual monitoring for this species in Delaware and the Great Smoky Mountains National Park is conducted in order to update occurrence records and to determine the rate of disease infection (DE NHP 1992, Rock 1992). Contact:

William McAvoy Botanist, Delaware Natural Heritage Program Division of Parks and Recreation Department of Natural Resources and Environmental Control, 89 Kings Highway P.O. Box 1401 Dover, DE 19903 Telephone: (302) 739-5285

Janet Rock Botanist, Great Smoky Mountains National Park Natural Resources Management 107 Park Headquarters Road Gatlinburg, TN 37738 Telephone: (615) 436-1244

Management Research Programs: Research into the identification and propagation of resistant strains of butternut to butternut canker disease is being conducted at the North Central Forest Experiment Station in St. Paul, Minnesota. This research focuses on three approaches: (1) the establishment of grafted clonal lines of butternut from putative resistant trees located in the field; (2) the development of methods to propagate these resistant lines so that resistant plant material will be available; and (3) the development of techniques to produce butternut in vitro by embryo, callus, and nodal explants and to develop an in vitro inoculation system to identify somaclones with resistance to butternut canker; (4) establish field plantings of material from objectives 2 and 3 and determine if field resistance is related to laboratory resistance (Skilling et al. 1990, 1992, 1993). Investigations are also being conducted to obtain samples of the canker fungus from throughout the range to determine if there is genetic or pathogenic variation within the fungus population. This information will assist in evaluating whether different isolates are needed to confirm resistance (Skilling et al. 1993). Detailed results of research conducted in the past three years may be found in progress reports prepared by Skilling et al. (1990, 1992, 1993).

Management Research Needs: As resistant strains of butternut trees to butternut canker disease are successfully propagated, management research will need to focus on reintroduction efforts and the preparation and maintenance of site conditions so that growth and reproduction of butternut will be optimized.

Biological Research Needs: In the years since detection of the butternut canker researchers have clarified several aspects of the disease; the major remaining conservation need is related to using resistant material and other techniques to retain and restore the species (Ostry and Woeste 2004). Resistance has been noted in many trees and may originate from natural phenotypic variants (Ostry and Woeste 2004) or possibly from hybridization with a close Asian relative, Japanese walnut (Juglans ailanthifolia) (Michler et al. 2005). Trees with possible resistance are being propagated and assessed but data are needed on the heritability of resistance and in general further genetic characterization is needed before classical breeding or genetic modification can be used to produce canker-resistant trees (Michler et al. 2005).

Comments:

Anyone observing what they believe to be disease-resistant trees (individual trees that appear to be canker-free within infected stands and are not residential shade trees) should contact Dr. Darroll Skilling, North Central Forest Experiment Station, 1992 Folwell Avenue, St. Paul, MN, 55108, telephone (612) 649-5116.

Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.” These plant materials are readily available from commercial sources.

Two hybrids show strong growth and extreme hardiness and produce nuts similar to the butternut in clusters of 10-15.

Juglans cinerea X J. regia = Juglans X quadrangulata

Juglans cinerea X J. ailantifolia = Juglans X bixbii

Butternut canker is killing the species over its whole range. The fungal pathogen (Sirococcus clavigignenti-juglandacearum) apparently was introduced from outside of North America. It was first reported from southwestern Wisconsin in 1967 but is believed to have spread from the southeastern US coastal region, where it first appeared about 40-50 years ago. The Forest Service estimated in 1995 that 77% of the butternuts in the Southeast were dead. The fungus infects trees through buds, leaf scars, and possibly insect wounds and other openings in the bark, rapidly killing small branches. Spores produced on branches are spread by rain, resulting in multiple, perennial stem cankers that eventually girdle and kill infected trees – these do not resprout. The cankered portions should be removed and destroyed and the wounds should be covered with fungicidal paint; leaves that might harbor fungus (brown leaf spot) should be destroyed.

A few healthy butternut trees have been found growing among canker-diseased and dying trees and may be resistant. Black walnut apparently is unaffected. A research coalition has been formed to locate surviving trees or populations, characterize sites, identify trees with putative resistance, develop screening methodology for disease resistance, study fungal physiology, and preserve germplasm.

Fire easily top-kills butternut and older trees rarely sprout from the root crown or stump. A single hot fire or repeated cool fires can effectively eliminate the species in mixed hardwood stands

There is commonly a zone of no-growth or inhibited growth around walnut trees, because they produce a naphthoquinone (juglone) that selectively inhibits growth of associated plants. Juglone is concentrated in root tissue and fruit husks, with lesser amounts in the leaves, catkins, buds, and inner bark.

Cultivars of this species have been selected for nut size and for  ease of cracking and extracting kernels. Several cultivars have  been named (14). Nuts are especially popular in New England for  making maple-butternut candy. Small amounts of wood are used for  cabinets, toys, and novelties.

Comments: J. cinerea is a highly valued lumber species because of its beautiful grain and soft texture. The nuts serve as feed for wildlife. The pigment from the husks was used to dye Confederate soldiers' uniforms during the Civil War.

Butternut is called "white walnut" because of its light-colored wood, which has a natural golden luster that becomes satin-like when polished. The wood is only moderately hard and saws and carves easily. It has been used for furniture, cabinetry, instrument cases, interior woodwork, including hand-carved wall panels and trim, and church decoration and altars. It is stocked in specialty lumberyards because little is cut annually.

Butternuts were often planted close to the house on farmsteads for their use as food. Kernels were used in baking and cultivars have been selected for nut size and for ease of cracking and extracting kernels.

They have been popular in New England for making maple-butternut candy. Early settlers used the fruit husks and inner bark to make orange or yellow dye and the root bark provided a laxative.

Stewardship Overview: Butternut is shade-intolerant, achieving its best growth in full sunlight and requires some form of disturbance, such as soil disturbance and the creation of canopy gaps for successful reproduction and establishment (Skilling 1993).

This species is critically threatened by the rapid spread of a canker fungus (Sirococcus clavigignenti-juglandacearum), which is killing trees (including sprouts and seedlings) throughout its range (Ostry et al. 1994). A majority of trees throughout the range may be infected with butternut canker, and recovery will be difficult. Many stands of butternut trees have been seriously impacted, leaving small clusters of very vulnerable individuals. The range of infection has apparently increased dramatically in recent time. For example, 77 percent of the trees have died in North Carolina and Virginia (Anderson 1993). A treatment with no known value (Skilling 1993) is the culling of infected trees to attempt to prevent the spread of the disease to other individuals within a stand or area. Considerable branch dieback is caused by Melanconis juglandis (E. and E.) Graves, a fungus that appears to attack trees of low vigor. Anderson and LaMadeleine (1978) reported that Melanconis oblongum Berk is associated with dieback in branches and twigs, causing deformation but not tree mortality. Although butternut canker is the primary global threat to this species, butternut is also threatened to some extent by plant succession in areas where the pre-settlement disturbance regime no longer exists, preventing the creation of open conditions necessary for the successful reproduction of this shade-intolerant species.

Conservation needs include compiling a more accurate assessment of the problem, such as determining the degree of damage, how widespread the disease is, the distribution of the species and the disease, and also assessing forest health and trends. Research needs include studies of the disease and disease vectors, and the development of improved screening techniques for determining resistant strains of butternut for germplasm preservation and testing. Research is being directed toward the identification and propagation of disease-resistant trees. The North Central Forest Experiment Station of the U.S. Forest Service is coordinating research with several state agencies, universities, and private individuals in a three-part study to: (1) plant grafted clones of butternut in the field from resistant trees; (2) find methods of propagating these clones; and (3) develop the techniques for producing butternut tissue ("somaclones") that can be inoculated in order to determine which germplasm is disease resistant (Forest Service News 1992). One management technique is simply to avoid cutting healthy trees such that potentially resistant individuals can ultimately be identified. It will be important to identify and monitor significant butternut stands to help determine disease invasion and spread. When apparently resistant trees are found, these individuals can be utilized for germplasm testing, propagation, and preservation.