Black Walnut

black walnut
walnut
eastern black walnut
American walnut

The eastern screech-owl roosts on the limbs of black walnut [6].

More info for the terms: forest, tree

Black walnut is a native, deciduous tree that can grow to a height of
125 feet (38 m) but ordinarily grows to around 80 feet (25 m) [10,43].
Black walnut develops a long, smooth trunk and a small rounded crown
when growing in the forest. In the open, the trunk forks low with a few
ascending and spreading coarse branches. The root system usually
consists of a deep taproot and several wide-spreading lateral roots.
The bark on young trees is dark and scaly but becomes darker with
rounded intersecting ridges on mature trees [17,39].

Black walnut is found throughout the eastern United States. It grows as
far north as southern Minnesota, southern Wisconsin, southern Michigan,
and southern Ontario. Isolated populations occur in the southern half of
New York, Vermont, western Massachusetts, and northwestern Connecticut.
Its range extends south to northwestern Florida, and to Mississippi,
Arkansas, and Louisiana except for the Mississippi Valley and Delta
regions. In the Midwest, isolated populations occur in eastern Texas,
western Oklahoma, central Kansas, and southeastern South Dakota
[8,29,30]. Black walnut is cultivated in Hawaii [45].

More info for the term: fire regime

Black walnut is well adapted to fire. Mature trees have thick bark and
naturally durable heartwood which make them relatively resistant to
damage and decay following fire [32,34,43].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".

More info for the term: fuel

Where the danger of fire exists, fuel buildup in young black walnut
plantations should be reduced by removing grasses and weeds [1,31,42].

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More info for the term: phanerophyte

Phanerophyte

More info for the term: tree

Black walnut is found on a variety of sites but grows best on deep,
well-drained neutral soils that are moist and fertile [43]. It grows
slowly on wet bottomlands, dry ridges, and slopes. Black walnut is
common on limestone soils [9,10] and grows extremely well on deep loams
and fertile alluvial deposits. Good agricultural soils are generally
favorable sites for black walnut. In the Appalachians, the best walnut
trees are found on bottomlands and coves below 4,000 feet (1,200 m) [5].

Principal associates are identified in the Distribution and Occurrence
frame. Other common tree associates include American elm (Ulmus
americana), hackberry (Celtis laevigata), green ash (Fraxinus
pennsylvanica), box elder (Acer negundo), and butternut (Juglans
cinerea) [29].

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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):

More info for the terms: hardwood, swamp

14 Northern pin oak
18 Paper birch
19 Gray birch - red maple
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
26 Sugar maple - basswood
27 Sugar maple
28 Black cherry - maple
40 Post oak - blackjack oak
42 Bur oak
43 Bear oak
44 Chestnut oak
45 Pitch pine
46 Eastern redcedar
52 White oak - black oak - northern red oak
53 White oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar - eastern hemlock
59 Yellow-poplar - white oak - northern red oak
60 Beech sugar maple
61 River birch - sycamore
62 Silver maple - American elm
64 Sassafras - persimmon
65 Pin oak - sweet gum
75 Shortleaf pine
76 Shortleaf pine - oak
78 Virginia pine - oak
79 Virginia pine
80 Loblolly pine - shortleaf pine
81 Loblolly pine
82 Loblolly pine - hardwood
91 Swamp chestnut oak - cherrybark oak
93 Sugarberry - American elm - green ash

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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
FRES12 Longleaf - slash pine
FRES13 Loblolly - shortleaf pine
FRES14 Oak - pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch

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

More info for the term: forest

K089 Black Belt
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K099 Maple - basswood
K100 Oak - hickory forest
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
K112 Southern mixed forest
K113 Southern floodplain forest
K114 Pocosin

Young black walnut trees are typically top-killed by most fires [18,31].

The nuts of black walnut furnish food for many rodents and make up about
10 percent of the diet of eastern fox squirrels [19,33]. The nuts are
also eaten by a variety of birds [2].

More info for the term: tree

Tree

Weed control is essential for the establishment of black walnut on sites
suitable for intensive culture [31].

An antagonism between black walnut and many other plants growing within
its root zone has been recognized and attributed to juglone, a toxic
substance found in the leaves, bark, nut husks, and roots of black
walnut trees. Many garden vegetables and several conifers are
susceptible to juglone [12,17,28].

Black walnut is particularly susceptible to European canker (Nectria
galligena). The infection spreads quite slowly, but infected trees
eventually die [29,43].

Black alder (Alnus glutinosa) and Russian olive (Elaeagnus angustifolia)
interplanted with black walnut increases black walnut's yield because of
their ability to increase available nitrogen in the soil [37,44].

Nutrient percentages (dry basis) for the nuts of black walnut are as
follows [41]:

crude protein 29.25
ether 60.25
crude fiber 1.03
ash 2.76
n-free extract 6.73
available protein 27.06
lignin 0.87
cellulose 2.01
tannin 0.25
calcium 0.01
magnesium 0.27
phosphorus 0.59

AL AR CT DE FL GA HI IA IL IN
KS KY LA MA MD MI MN MO MS NC
NE NJ NY OH OK PA SC SD TN TX
VA VT WI WV ON

The nuts of black walnut are used as food by humans and are harvested
commercially [26]. The nuts are eaten plain or with honey and used to
flavor cakes, candy, and ice cream [14]. Native Americans used the nuts
for food and extracted black dye from the roots. The black walnut is
mentioned in Native American creation myths [14]. Black walnut is
cultivated as an ornamental [40].

The ground shells of black walnut are used as a nonslip agent in
automobile tires, as an air pressure propellant in strip paints, and as
a filtering agent for scrubbers in smoke stacks. The automobile
industry uses the ground shell products to deburr precision gears, and
the airline industry uses the ground shells to clean jet engines [43].

Although not considered a choice browse, black walnut leaves are
palatable to white-tailed deer [16].

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More info for the term: fruit

Black walnut normally begins flowering about mid-April in the southern
part of its geographic range and mid-June in the northern part of its
range. The fruit ripens in September or October of the same year,
dropping shortly after the leaves fall [10,29].

More info for the term: root collar

Small 20- to 30-year-old black walnut trees will usually sprout from the
root collar or stump when top-killed by fire. Sprouting is more erratic
from trees 30 years and older [31,43].

More info for the terms: caudex, root crown, seed

survivor species; on-site surviving root crown or caudex
off-site colonizer; seed carried by animals or water; postfire yr 1&2

More info for the terms: root crown, seed, tree

Seed production: Black walnut produces abundant seed crops irregularly,
perhaps twice in 5 years. Although open-grown trees produce seed as
early as 8 years after planting, the minimum seed-bearing age for
commercial quantities of seed is about 12 years. Best seed production
begins when the tree is about 30 years old and continues for another 100
years [31,43].

Dispersal: Black walnut seed is heavy. The seeds are dispersed by
squirrels carrying seed from beneath the tree and burying them at a
distance [29,36].

Seedling development: Many black walnut seedlings germinate from the
nuts cached by squirrels in the fall. Normal freezing and thawing
usually causes the seeds to break dormancy the following spring, but
germination is often delayed, sometimes until the second year [3,35].

Vegetative reproduction: Small black walnut trees usually sprout from
the stump when they are cut or killed back by fire. Shoots originating
high on the older stumps often decay, but shoots from the root crown
generally are free from defect [22,43].

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More info for the terms: climax, forest, tree

Black walnut is classified as shade intolerant. In mixed forest stands,
it must be dominant to survive, although it can survive in the
relatively light shade of black locust [43]. Black walnut is found in
many of the climax associations but because of its intolerance is not
classified as a climax tree in the strict sense. In general, black
walnut maintains itself in most stands as scattered single trees
occupying openings in the canopy [15].

The currently accepted scientific name for black walnut is Juglans nigra
L. [21]. There are no recognized subspecies, varieties, or forms.
Black walnut and butternut (J. cinerea) often grow together but
apparently never cross naturally [43].

More info for the term: competition

Black walnut has been successfully planted on surface mined areas in the
eastern United States [4,7]. In southwestern Indiana, black walnut had
a 30 to 50 percent increase in survival rate on old mine field sites
where weed competition had been chemically controlled or removed [4].

Characteristics and properties: Black walnut wood is heavy, strong, and
highly resistant to shock. It ranks with the most durable U.S.
hardwoods, including cedars (Thuja spp.), chestnuts (Castanea spp.), and
black locust (Robinia pseudoacacia). It can be satisfactorily kiln
dried and holds it shape well after seasoning. Black walnut is normally
straight grained, is worked easily with hand tools, and has excellent
machining properties. When finished, the wood takes on a smooth velvety
surface and a handsome grain pattern [25,29].

Principal uses: Black walnut is used principally for dining room and
bedroom furniture; bookcases; desks; tables; radio, television,
phonograph, and piano cabinets; and as an interior finish in cafes and
public buildings [24]. The veneer is used for the highest grade
cabinets and plywood panels. Figured black walnut stocks are prized for
expensive shotguns and sporting rifles [8,29].