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''Juglans nigra'', the eastern American black walnut, is a species of
deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...
tree in the
walnut A walnut is the edible seed of any tree of the genus '' Juglans'' (family Juglandaceae), particularly the Persian or English walnut, '' Juglans regia''. They are accessory fruit because the outer covering of the fruit is technically an i ...
family,
Juglandaceae The Juglandaceae are a plant family known as the walnut family. They are trees, or sometimes shrubs, in the order Fagales. Members of this family are native to the Americas, Eurasia, and Southeast Asia. The nine or ten genera in the family have ...
, native to central and eastern
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
, growing mostly in
riparian zone A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...
s. Black walnut is susceptible to thousand cankers disease, which provoked a decline of walnut trees in some regions. Black walnut is allelopathic, releasing chemicals from its roots and other tissues that may harm other organisms and give the tree a competitive advantage, but there is no
scientific consensus Scientific consensus is the generally held judgment, position, and opinion of the majority or the supermajority of scientists in a particular field of study at any particular time. Consensus is achieved through scholarly communication at confer ...
that this is a primary competitive factor. Black walnut is an important tree commercially, as the wood is a deep brown color and easily worked. Walnut
seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s ( nuts) are cultivated for their distinctive and desirable taste. Walnut trees are grown for lumber and food, and processors have found additional markets for even the tough outer hulls by finely grinding them for use in products such as abrasive cleansers. Many
cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...
s have been developed for improved quality wood or nuts. In 2017, the
United States Department of Agriculture The United States Department of Agriculture (USDA) is an executive department of the United States federal government that aims to meet the needs of commercial farming and livestock food production, promotes agricultural trade and producti ...
valued U.S. walnut timber at $530 billion. A significant amount is grown in
Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...
.


Description

The tree grows to tall. Under forest competition, it develops a tall and straight trunk. When grown in an open area it has a short trunk and broad crown. The
bark Bark may refer to: Common meanings * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...
is typically grey-black and deeply furrowed into thin ridges that gives the bark a diamond-shaped pattern. The
pith Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ex ...
of the twigs is chambered and light brown. The
bud In botany, a bud is an undeveloped or Plant embryogenesis, embryonic Shoot (botany), shoot and normally occurs in the axil of a leaf or at the tip of a Plant stem, stem. Once formed, a bud may remain for some time in a dormancy, dormant conditi ...
s are pale silky and covered in downy hairs. The terminal buds are ovate, and long, and slightly longer than broad, the lateral buds are smaller and superposed. The
leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
are pinnately compound and alternately arranged on the stem. They are long, typically even-pinnate but there is heavy variation among leaves. The stems have 15–23 leaflets, when terminal leaf is included, with the largest leaflets located in the center, long and broad. The leaflets have a rounded base and a long pointed ( acuminate) tip as well as having a serrated edge. The leaves are overall dark green in color and are typically hairy on the underside. The leaf scar has three prominent bundle scars and has a notch on the side that points toward the tip of the branch (distal side). Black walnut is
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...
. The male ( staminate) flowers are in drooping
catkins A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). It contains many, usually unisexual flowers, arranged cl ...
long. These are borne from axillary buds on the previous year's growth. The female ( pistillate) flowers are terminal, in clusters of two to five on the current year's growth. During the summer/autumn, a spherical fruit (nut) ripens. It comprises a brownish-green, semifleshy husk and a brown, corrugated nut. The whole fruit, including the husk, falls in October; the seed is relatively small and very hard. Most parts of the tree including leaves, stems, and fruit
husk Husk (or hull) in botany is the outer shell or coating of a seed. In the United States, the term husk often refers to the leafy outer covering of an Ear (botany), ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes t ...
s have a very characteristic pungent or spicy odor. This odor is lacking in the nut itself.


Similar species

''J. cinerea'' (the butternut) is similar in leaf shape and range. The fruits are quite different, as black walnut fruits are spherical and butternuts are more oval-oblong. When a fruit is not available, two species can be differentiated based on the leaf scars: the butternut's has a flat upper edge and with a velvety ridge above that flat part, but black walnut's is indented with no hairy ridge.


Distribution and habitat

The species is native to
North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
. It grows mostly in
riparian zone A riparian zone or riparian area is the interface between land and a river or stream. In some regions, the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor, and riparian strip are used to characterize a ripari ...
s, from southern
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
, west to southeast
South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...
, south to
Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...
, northern
Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...
and southwest to central
Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
. Wild trees in the upper Ottawa Valley may be an isolated native population or may have derived from planted trees. The range of the black walnut is strongly correlated with low maximum vapour-pressure deficit.


Ecology

Black walnut is primarily a
pioneer species Pioneer species are resilient species that are the first to colonize barren environments, or to repopulate disrupted biodiverse steady-state ecosystems as part of ecological succession. Various kinds of events can create good conditions for pi ...
similar to red and silver maple and black cherry. Because of this, black walnut is a common weed tree found along roadsides, fields, and forest edges in the eastern US. It will grow in closed forests, but is classified as shade intolerant; this means it requires full sun for optimal growth and nut production. Black walnut's native range extends across much of the eastern US. It is absent from the coastal plain south of
North Carolina North Carolina ( ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, South Carolina to the south, Georgia (U.S. stat ...
as well as the Mississippi Valley, and does not occur in the northern tier of the eastern US, where the frost-free season is too short for the nuts to develop. Its western range extends all the way to the eastern Great Plains, beyond which climate conditions become too dry for it. Black walnut is one of the most abundant trees in the eastern US, particularly the Northeast, and its numbers are increasing due to epidemics that have affected other tree species, including emerald ash borer, chestnut blight, butternut canker, wooly hemlock adelgid, dogwood anthracnose, Dutch elm disease, and spongy moth infestations. Widespread clear-cutting of oaks due to spongy moth damage in the 1970s–1980s particularly aided in the tree's spread. The aggressive competitive strategy of black walnut such as its fast growth, alleopathic chemicals, and rodent-dispersed seeds, have also contributed. The nuts are food for many rodents and make up to 10% of the diet of eastern fox squirrels. The nuts are also eaten by species of birds. The leaves are browsed by
white tailed deer The white-tailed deer (''Odocoileus virginianus''), also known Common name, commonly as the whitetail and the Virginia deer, is a medium-sized species of deer native to North America, North, Central America, Central and South America. It is the ...
, although they are not a preferred food. Where the range of the eastern black walnut overlaps that of the Texas black walnut ('' J. microcarpa''), the two species sometimes interbreed, producing populations with characteristics intermediate between the two species. ''J. nigra'' and ''J. cinerea'' often grow in the same range as well but they do not hybridize naturally. The tree's roots often form endomycorrhizal relationships with fungi in the genus ''Glomus''. Some endomycorrhizal relations improve the plant's growth. Species often associated with ''J. nigra'' include yellow-poplar (''Liriodendron tulipifera''), white ash (''Fraxinus americana''), black cherry (''Prunus serotina''), basswood (''Tilia americana''), American beech (''Fagus grandifolia''), sugar maple (''Acer saccharum''),
oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...
s (''Quercus'' spp.), and hickories (''Carya'' spp.). Near the western edge of its range, black walnut may be confined to floodplains, where it grows either with
American elm ''Ulmus americana'', generally known as the American elm or, less commonly, as the white elm or water elm, is a species of elm native to eastern North America. The trees can live for several hundred years. It is a very hardy species that can ...
(''Ulmus americana''), common hackberry (''Celtis occidentalis''),
green ash Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
(''Fraxinus pennsylvanica''), and boxelder (''Acer negundo''), or with basswood and red oak (''Quercus rubra'') on lower slopes and other favorable sites.


Pests

Maggot A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, hoverflies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and cr ...
s (larvae of '' Rhagoletis completa'' and '' Rhagoletis suavis'') in the husk are common, though more a nuisance than a serious problem for amateurs, who may simply remove the affected husk as soon as infestation is noticed. The maggots develop entirely within the husk, thus the quality of the nutmeat is not affected. However, infestations of maggots are undesirable because they make the husk difficult to remove and are unsightly. Maggots can be serious for commercial walnut growers, who tend to use chemical treatments to prevent damage to the crop. Some non-chemical controls also exist, such as removing and disposing of infested nuts. The walnut weevil (''
Conotrachelus retentus ''Conotrachelus retentus'', the black walnut curculio, is a species of true weevil in the beetle family Curculionidae. It is found in North America. Larvae feed on the developing walnut, while adults feed on foliage. Adult weevils rarely leave th ...
'') grows to long as an adult. The adult sucks plant juices through a snout. The eggs are laid in fruits in the spring and summer. Many nuts are lost due to damage from the larvae, which burrow through the nut shell. Black walnut is affected by European canker ('' Neonectria galligena''). The infection spreads slowly but infected trees eventually die. The walnut caterpillar ('' Datana integerrima'') and fall webworm ('' Hyphantria cunea'') are two of the most serious pests, they commonly eat the foliage in midsummer and continue into autumn. Codling moth (''
Cydia pomonella The codling moth (''Cydia pomonella'') is a member of the Lepidopteran family Tortricidae. They are major Agricultural pests, pests to agricultural crops, mainly fruits such as apples and pears, and a codling moth larva is often called an "wikt: ...
'') larvae eat walnut kernels, as well as apple and pear seeds. Important leaf sucking insects include species of
aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...
s and plant lice including ('' Monellia'' spp. and '' Monelliopsis'' spp.), which suck the juices from leaves and often deposit a sticky substance called "honey-dew" on the leaf surface that may turn black and prevent photosynthesis; and the walnut lace bug ('' Corythucha juglandis''), which causes damage when the adults and nymphs suck the sap from the lower surfaces of walnut leaflets. A disease complex known as thousand cankers disease has been threatening black walnut in several western states. This disease has recently been discovered in Tennessee, and could potentially have devastating effects on the species in the eastern United States. Vectored by the walnut twig beetle ('' Pityophthorus juglandis''), a fungus, '' Geosmithia morbida'', spreads into the wood around the galleries carved by the small beetles. The fungus causes cankers that inhibit the movement of nutrients in black walnut, leading to crown and branch dieback, and ultimately death.


Allelopathy

While black walnut is considered allelopathic, meaning it excretes chemicals into its environment that harm competition, research from 2019 has questioned whether this long-held belief holds up to scientifically rigorous examination. Many publications that have repeated claims of black walnut allelopathy cite a very limited set of dated research literature, which has not held up to scientific scrutiny. Anecdotally, records of walnut toxicity to other plants have been observed as far back as the first century when
Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...
wrote: "The shadow of walnut trees is poison to all plants within its compass." Like other walnuts, the roots, inner bark, nut husks, and leaves contain a nontoxic chemical called hydrojuglone; when exposed to air or soil compounds it is oxidized into
juglone Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is a phenolic organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but s ...
that is biologically active and acts as a respiratory inhibitor to some plants. Juglone is poorly soluble in water and does not move far in the soil and will stay most concentrated in the soil directly beneath the tree. Even after a tree is removed the soil where the roots once were will still contain juglone for several years after the tree is removed as more juglone will be released as the roots decay. Well drained and aerated soils will host a healthy community of soil microbes and these microbes will help to break down the juglone. Symptoms of juglone poisoning include foliar yellowing and wilting. A number of plants are particularly sensitive. Apples, tomatoes, pines, and birch are poisoned by juglone, and as a precaution, should not be planted in proximity to a black walnut.


Interaction with horses

Horses are susceptible to
laminitis Laminitis is a disease of the feet of ungulates, found mostly in horses and cattle involving inflammation of the laminae. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, and increased temperatur ...
from exposure to black walnut wood in bedding.


Cultivation

The fruit production tends to occur irregularly with some years producing larger crops than others (see mast year). Fruiting may begin when the tree is 4–6 years old, but large crops take 20 years. Total lifespan of ''J. nigra'' is about 130 years. Like other trees of the order
Fagales The Fagales are an order of flowering plants in the rosid group of dicotyledons, including some of the best-known trees. Well-known members of Fagales include: beeches, chestnuts, oaks, walnut, pecan, hickory, birches, alders, hazels, hornb ...
, such as oaks, hickories, chestnuts, and birches, it is monoecious, with wind-pollinated catkins. Male and female flowers are in separate spikes, and the female flowers typically appear before the male on a single tree (
dichogamy Sequential hermaphroditism (called dichogamy in botany) is one of the two types of hermaphroditism, the other type being simultaneous hermaphroditism. It occurs when the organism's sex changes at some point in its life. A sequential hermaphrodit ...
). As a consequence,
self-pollination Self-pollination is a form of pollination in which pollen arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms) of the same plant. The term cross-pollination is used for the opposite case, where pollen from ...
is unlikely. However, individual trees are commonly self-compatible; if they are not pollinated by neighboring trees, they may set self-fertilized seeds. For maximum seed germination, the seeds should be cold-moist stratified for 3–4 months, although the exact time depends on the seed source. The seedlings emerge in April or May. While most trees with taproots have a reputation for slow growth, black walnut is an exception and can achieve very rapid growth in the seedling stage, typically their first year and even more in the second year. Black walnut will not leaf out until temperatures have warmed sufficiently. Leafout in spring is initiated when daytime highs reach approximately and leaf drop in fall when daytime highs fall below . As such, the exact timing will vary in different regions of the U.S. and depending on the weather conditions from year to year, leafout is typically early April in the southern part of its range and sometimes not until the end of May or beginning of June in cooler areas. Leaf drop in fall may begin in late September in cooler regions and not until November in southern areas. Black walnut is more resistant to frost than '' J. regia'' (the English or Persian walnut), but thrives best in the warmer regions of fertile, lowland soils with high water tables, although it will also grow in drier soils, but much more slowly. Some specimens have been found to survive frosts down to . Some soils preferred by black walnut include alfisol and
entisol Entisols are soils, as defined under USDA soil taxonomy, that do not show any profile development other than an A-horizon (or “A” horizon). Entisols have no diagnostic horizons, and are unaltered from their parent material, which could ...
soil types. Black walnut grows best on sandy loam, loam, or silt loam type soils but will also grow well on silty clay loam soils. It prefers these soils because they hold large quantities of water, which the tree draws from during rainless periods.


Planting

Black walnut has a strong
taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproot ...
, which makes the seedlings resilient, but difficult to transplant. While its primary native region is the Midwest and east-central United States, the black walnut was introduced into Europe, likely in the year 1629, where it has gained economic significance. It is also cultivated in Hawaii. It is cultivated as a forest tree for its high-quality wood. Black walnut plantings can be made to produce timber, nuts, or both timber and nuts. Patented timber-type trees were selected and released from
Purdue University Purdue University is a Public university#United States, public Land-grant university, land-grant research university in West Lafayette, Indiana, United States, and the flagship campus of the Purdue University system. The university was founded ...
in the early 1990s. These trees have been sporadically available from nurseries. Varieties include Purdue #1, which can be used for both timber and nut production, though nut quality is poor compared to varieties selected specifically as nut producers. Grafted, nut-producing trees are available from several nurseries operating in the U.S. Selections worth considering include Thomas, Neel #1, Thomas Myers, Pounds #2, Stoker, Surprise, Emma K, Sparrow, S127, and McGinnis. Several older varieties, such as Kwik Krop, are still in cultivation; while they make decent nuts, they would not be recommended for commercial planting. Pollination requirements should be considered when planting black walnuts. As is typical of many species in Juglandaceae, ''J. nigra'' trees tend to be monoecious, i.e.. produce
pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...
first and then pistillate flowers or else produce pistillate flowers and then pollen. An early pollen-producer should be grouped with other varieties that produce pistillate flowers so all varieties benefit from overlap. Cranz, Thomas, and Neel #1 make a good pollination trio. A similar group for more northern climates would be Sparrow, S127, and Mintle. Sometimes black walnut is planted as part of reclaiming mines. When growing young trees weed control is critical for healthy establishment of the trees, without weed control the young trees are harmed significantly in their growth rate.


Commercial

Black walnuts are shelled commercially in the United States. With about 65% of the U.S.'s annual wild harvest, the U.S. state of
Missouri Missouri (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...
is home to the world's largest processor and distributor of black walnuts, which the Missouri Department of Conservation considers to be the state's most valuable timber. In 1990, Missouri named the "Eastern Black Walnut" as its official tree nut. Missouri's largest processing plant is operated by Hammons Products in
Stockton, Missouri Stockton is a city and the county seat of Cedar County, Missouri, United States. The population was 1,683 at the 2020 census. History Stockton was platted in 1846. It was originally named Lancaster, but was renamed Fremont in 1847 in honor of ...
. NPR affiliate KCUR stated in an article that "Ralph Hammons began the company in 1946 with a nut cracking machine acquired from Tennessee." The Stockton ''Black Walnut Festival'', which has been held annually since 1961, "brings the community together for a 3-day event jam-packed with activities including a carnival, tractor pull, nut roll and 2-hour parade," stated Alexa Hodges in a VOX article.


Nut processing by hand

The extraction of the kernel from the fruit of the black walnut is difficult. The thick, hard shell is tightly bound by tall ridges to a thick husk. Rolling the nut underfoot on a hard surface such as a driveway is a common method; commercial huskers use a car tire rotating against a metal mesh. Some take a thick plywood board and drill a nut-sized hole in it (from one to two inches in diameter) and smash the nut through using a hammer. The nut goes through and the husk remains behind. American pioneers let the nuts dry in the sun, then removed the husks and let the kernels dry—making them less bitter. The shell itself is thicker than that of the English walnut, and there are additional, thick internal walls tightly surrounding the nutmeat. Walnuts are too tough and too large to be opened with a standard nutcracker, but simply cracking the shell open with a rock results in smashed and shattered nutmeats mixed with shell, unless done with some care and skill—and it is still nearly impossible to extract an intact half this way. As a result, a number of home walnut-cracking devices have been produced, involving vices, cams, or levers. While the flavor of the ''Juglans nigra'' kernel is prized, the difficulty in preparing it may account for the wider popularity and availability of the English walnut.


Ornamental

''J. nigra'' is also grown as a specimen ornamental tree in parks and large gardens, growing to tall by broad. It has gained the
Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...
's
Award of Garden Merit The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...
.


Uses


As food

Black walnut kernels are edible. The nut provides a robust, distinctive, natural flavor and crunch as a food ingredient. Common uses include ice cream, bakery goods and confections. Consumers include black walnuts in traditional treats, such as
cake Cake is a flour confection usually made from flour, sugar, and other ingredients and is usually baked. In their oldest forms, cakes were modifications of bread, but cakes now cover a wide range of preparations that can be simple or elabor ...
s,
cookie A cookie is a sweet biscuit with high sugar and fat content. Cookie dough is softer than that used for other types of biscuit, and they are cooked longer at lower temperatures. The dough typically contains flour, sugar, egg, and some type of ...
s,
fudge ''Fudge'' is a generic role-playing game system for use in freeform role-playing games. The name "''FUDGE''" was once an acronym for ''Freeform Universal Donated'' (later, ''Do-it-yourself'') ''Gaming Engine'' and, though the acronym has since b ...
, and pies, during the fall holiday season. The nuts are versatile for uses in other foods, such as
salad A salad is a dish consisting of mixed ingredients, frequently vegetables. They are typically served chilled or at room temperature, though some can be served warm. Condiments called '' salad dressings'', which exist in a variety of flavors, a ...
s,
fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
,
pork Pork is the culinary name for the meat of the pig (''Sus domesticus''). It is the most commonly consumed meat worldwide, with evidence of pig animal husbandry, husbandry dating back to 8000–9000 BCE. Pork is eaten both freshly cooke ...
,
chicken The chicken (''Gallus gallus domesticus'') is a domesticated subspecies of the red junglefowl (''Gallus gallus''), originally native to Southeast Asia. It was first domesticated around 8,000 years ago and is now one of the most common and w ...
, vegetables and pasta dishes. Tapped in spring, the tree yields a sweet sap that can be drunk or concentrated into syrup or sugar that is not unlike the sap of sugar maple.


Nutrition

Black walnut kernels are 5% water, 59%
fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...
, 24%
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
, and 10%
carbohydrate A carbohydrate () is a biomolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. The typical hydrogen-to-oxygen atomic ratio is 2:1, analogous to that of water, and is represented by the empirical formula (where ''m'' and ''n'' ...
s. In a reference amount of , walnuts supply 619
calorie The calorie is a unit of energy that originated from the caloric theory of heat. The large calorie, food calorie, dietary calorie, kilocalorie, or kilogram calorie is defined as the amount of heat needed to raise the temperature of one liter o ...
s and several
micronutrient Micronutrients are essential chemicals required by organisms in small quantities to perform various biogeochemical processes and regulate physiological functions of cells and organs. By enabling these processes, micronutrients support the heal ...
s in "rich" amounts (20% or more of the
Daily Value In the U.S. and Canada, the Reference Daily Intake (RDI) is used in nutrition labeling on food and dietary supplement products to indicate the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97� ...
, DV), including the
dietary minerals In the context of nutrition, a mineral is a chemical element. Some "minerals" are essential for life, but most are not. ''Minerals'' are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essen ...
manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...
(169% DV) and
copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
(156% DV), among others, and the B vitamins, B6 (34% DV) and
pantothenic acid Pantothenic acid (vitamin B5) is a B vitamin and an essential nutrient. All animals need pantothenic acid in order to synthesize coenzyme A (CoA), which is essential for cellular energy production and for the synthesis and degradation of prote ...
(33% DV). Black walnut kernels are a moderate source (10–19% DV) of vitamin E and
riboflavin Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
.Source in table Analysis of black walnut fat content showed the most prevalent
fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
s are
linoleic acid Linoleic acid (LA) is an organic compound with the formula . Both alkene groups () are ''cis''. It is a fatty acid sometimes denoted 18:2 (n−6) or 18:2 ''cis''-9,12. A linoleate is a salt or ester of this acid. Linoleic acid is a polyunsat ...
(33.8%), followed by
oleic acid Oleic acid is a fatty acid that occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, although commercial samples may be yellowish due to the presence of impurities. In chemical terms, oleic acid is cl ...
(15.3%), alpha-linolenic acid (2.7%),
palmitic acid Palmitic acid (hexadecanoic acid in IUPAC nomenclature) is a fatty acid with a 16-carbon chain. It is the most common saturated fatty acid found in animals, plants and microorganisms.Gunstone, F. D., John L. Harwood, and Albert J. Dijkstra. The ...
(1.9%), and
stearic acid Stearic acid ( , ) is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula . The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid ...
(1.5%).


Dye

Black walnut
drupe In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed ...
s contain juglone (5-hydroxy-1,4-naphthoquinone), plumbagin (yellow quinone pigments), and
tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...
. These compounds cause walnuts to stain cars, sidewalks, porches, and patios, in addition to the hands of anyone attempting to shell them. The brownish-black dye was used by early American settlers to dye hair. According to Eastern Trees in the Petersen Guide series, black walnuts make a yellowish-brown dye, not brownish-black. The apparent confusion is easily explained by the fact that the liquid (dye) obtained from the inner husk becomes increasingly darker over time, as the outer skin darkens from light green to black. Extracts of the outer, soft part of the drupe are still used as a
natural dye Natural dyes are dyes or colorants derived from plants, invertebrates, or minerals. The majority of natural dyes are vegetable dyes from plant sources—roots, berry, berries, Bark (botany), bark, leaf, leaves, and wood—and other biological sourc ...
for handicrafts. The tannins present in walnuts act as a mordant, aiding in the dyeing process, and are usable as a dark ink or wood stain.


Shells

Walnut shells are often used as an abrasive in sand blasting or other circumstances where a medium hardness grit is required. The hard black walnut shell is also used commercially in abrasive cleaning, a filtering agent in scrubbers in smoke stacks, cleaning jet engines, cosmetics, and oil well drilling and water filtration. Additionally, the husks are ground into an ingredient in exfoliating cosmetics.


Wood

Black walnut is highly prized for its dark-colored, straight grained, true heartwood. It is heavy, strong, shock resistant and yet can be easily split and worked. Along with cedars ( ''Thuja spp.''), chestnut ( ''Castanea spp''.), and black locust (''
Robinia pseudoacacia ''Robinia pseudoacacia'', commonly known as black locust, is a medium-sized hardwood deciduous tree, belonging to the tribe Robinieae of the legume family Fabaceae. It is native to a few small areas of the United States, but it has been widely pl ...
'') black walnut is one of the most durable hardwoods in the US. The wood can be kiln dried and holds its shape well after seasoning, which makes this wood even more attractive for wood working. Walnut wood has historically been used for gun stocks, furniture, flooring, paddles, coffins, and a variety of other wood products. Black walnut has a density of 660 kg per cubic meter (41.2 lb/cubic foot), which makes it less dense than oak.


Largest trees

The U.S. national champion black walnut is on a residential property on Sauvie Island,
Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
. It is
diameter at breast height Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements. Tree trunks are measured at the height of an adult's breast, ...
and tall, with a crown spread of . The tallest black walnut in Europe is located in the Woluwe Park in the city of Sint-Pieters-Woluwe, Brussels, Belgium. It has a circumference of , height of exactly (measured by laser), and was planted around 1850 (± 10 years). The largest black walnut in Europe is located in the Castle Park in the city of Sereď, Slovakia. It has a circumference of , height of and estimated age of 300 years.


See also

* Taxonomy of walnut tree varieties *
Anthelmintic Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them without causing significant damage to the host. They may also ...


References


Further reading

* *Petrides, G. A. and Wehr, J. (1998). ''Eastern Trees''. Houghton Mifflin Company. *Little, Elbert L. (1980) ''National Audubon Society Field Guide to North American Trees: Eastern Edition.'' Borzoi Books.


External links

*A variety index and characteristics guide is available fro
Missouri Extension

Guide to "Growing Black Walnuts for Nut Production"
University of Missouri Center for Agroforestry *
Walnut Council.org homepageFlora of North America: ''Juglans nigra''

Range distribution Map:Set of Black Walnut ID photos and range mapBlack Walnut Diagnostic photos: tree, leaves, bark and fruit
*
Juglans nigra
' - information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN) {{Authority control nigra Edible nuts and seeds Flora of the Appalachian Mountains Symbols of Missouri Trees of humid continental climate Plants described in 1753 Taxa named by Carl Linnaeus Plant dyes Garden plants of North America Ornamental trees Flora of Texas Trees of Northern America