Pignut Hickory
Encyclopedia
Carya glabra, the Pignut hickory, is a common but not abundant species in the oak
-hickory
forest association in the Eastern United States
and Canada
. Other common names are pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, and broom hickory. The pear-shaped nut
ripens in September and October and is an important part of the diet of many wild animals. The wood
is used for a variety of products, including fuel for home heating.
and westward through Louisiana and along the Gulf Coast to Alabama
through Mississippi
. It extends through parts of East Texas
to Louisiana
, Arkansas
, Missouri
and extreme southeastern Iowa
. Its range further includes Massachusetts
and the southwest corner of New Hampshire
westward through southern Vermont
to central Lower Peninsula of Michigan
and Illinois
.
The best development of this species is in the lower Ohio River
Basin. It prevails over other species of hickory in the Appalachian forests. Pignut makes up much of the hickory harvested in Kentucky
, West Virginia
, the Cumberland Mountains
of Tennessee
, and the hill country of the Ohio Valley.
Pignut Hickory is also found in Canada in southern Ontario
. It does however have a limited range and is resticted to the Niagara Peninsula
, southern Halton Region, the Hamilton
area along western Lake Ontario
, and southward along the northern shore of Lake Erie
and pockets of extreme southwestern Ontario.
with an average annual precipitation
of 760 to 2,030 mm (30 to 80 in) of which 510 to 1,020 mm (20 to 40 in) is rain
during the growing season. Average snowfall varies from little to none in the South to 2,540 mm (100 in) or more in the mountains of West Virginia
, southeastern New York
, and southern Vermont
(25).
Within the range of pignut hickory, average annual temperatures vary from 7°C (45°F) in the north to 21°C (70°F) in Florida. Average January temperature varies from -4° to 16°C (25° to 60°F) and average July temperature varies from 21° to 27°C (70° to 80°F). Extremes of 46° and -30°C (115° and -22°F) have been recorded within the range. The growing season
varies by latitude
and elevation
from 140 to 300 days.
Mean annual relative humidity
ranges from 70 to 80 percent with small monthly differences; daytime relative humidity often falls below 50% while nighttime humidity approaches 100%.
Mean annual hours of sunshine
range from 2,200 to 3,000. Average January sunshine varies from 100 to 200 hours, and July sunshine from 260 to 340 hours. Mean daily solar radiation ranges from 12.57 to 18.86 million J m± (300 to 450 langleys). In January daily radiation varies from 6.28 to 12.57 million J m± (150 to 300 langleys), and in July from 20.95 to 23.04 million J m± (500 to 550 langleys).
According to one classification of climate (20), the range of pignut hickory south of the Ohio River
, except for a small area in Florida, is designated as humid, mesothermal
. That part of the range lying north of the Ohio River is designated humid, mesothermal. Part of the species range in peninsular Florida is classed as subhumid, mesothermal. Mountain
s in Pennsylvania, West Virginia, North Carolina, and Tennessee are classed as wet, microthermal
, and mountains in South Carolina and Georgia are classed as wet, mesothermal. Throughout its range, precipitation is rated adequate during all seasons.
. In the Great Smoky Mountains
pignut hickory has been observed on dry sandy soils at low elevations. Whittaker (27) placed pignut in a submesic class and charted it as ranging up to 1480 m (4,850 ft)-the hickory with the greatest elevational range in the Great Smoky Mountains. In southwest Virginia, south-facing upper slopes from 975 to 1050 m (3,200 to 3,445 ft) of Beanfield Mountain are dominated by pignut hickory, northern red oak Quercus rubra), and white oak (Q. alba). This site is the most xeric habitat
on the mountain because of high insolation
, 70 percent slopes, and medium- to coarse-textured soils derived from Clinch sandstone. Mid-elevation slopes from 800 to 975 m (2,625 to 3,200 ft) are dominated by chestnut oak (Q. prinus), northern red oak, and pignut hickory and coincide with three shale
formations (12).
The range of pignut hickory encompasses 7 orders
, 12 suborders, and 22 great groups of soil
s (24,25). About two-thirds of the species range is dominated by Ultisols
, which are low in bases and have subsurface horizons of clay
accumulation. They are usually moist but are dry during part of the warm season. Udults is the dominant suborder and Hapludults and Paleudults are the dominant great groups. These soils are derived from a variety of parent materials-sedimentary and metamorphic rocks, glacial till, and in places varying thickness of loess
-which vary in age from Precambrian
to Quaternary
.
A wide range of soil fertility exists as evidenced by soil orders-Alfisols
and Mollisols
which are medium to high in base saturation to Ultisols which are low in base saturation (24). Pignut hickory responds to increases in soil nitrogen similarly to American beech (Fagus grandifolia), sugar maple (Acer saccharum), and blackgum (Nyssa sylvatica) (15). These species are rated as intermediate in nitrogen deficiency tolerance and consequently are able to grow with lower levels of nitrogen than are required by "nitrogen- demanding" white ash (Fraxinus americana), yellow-poplar (Liriodendron tulipifera
), and American basswood (Tilia americana
). Hickories are considered "soil improvers" because their leaves
have a relatively high calcium
content.
forest association commonly called oak-hickory, but they are not generally abundant (18). Locally, hickories may make up to 20 to 30 percent of stand basal area, particularly in slope and cove forests below the escarpment
of the Cumberland Plateau
(23) and in second-growth forests in the Cumberland Mountains
, especially on benches
(14). It has been hypothesized that hickory will replace chestnut (Castanea dentata) killed by the blight (Cryphonectria parasitica) in the Appalachian Highlands (10,12). On Beanfield Mountain in Giles County
, Virginia
, the former chestnut-oak complex has changed to an oak-hickory association over a period of 50 years. This association is dominated by pignut hickory with an importance value of 41.0 (maximum value = 300), northern red oak (36.0), and chestnut oak (25.0). White oak, red maple (Acer rubrum), and sugar maple are subdominant species.
Pignut hickory is an associated species in 20 of the 90 forest cover types listed by the Society of American Foresters
for the eastern United States (6):
-Blackjack 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
59 Yellow-Poplar-White Oak-Northern Red Oak
64 Sassafras
-Persimmon
110 Black Oak
76 Shortleaf Pine-Oak
78 Virginia Pine
-Oak
79 Virginia Pine
80 Loblolly Pine
-Shortleaf Pine
81 Loblolly Pine
82 Loblolly Pine-Hardwood
83 Longleaf Pine-Slash Pine
Because the range of pignut hickory is so extensive, it is not feasible to list the associated tree
s, shrub
s, herb
s, and grass
es, which vary according to elevation
, topographic conditions, edaphic
features, and geographic locality.
ing- Hickories are monoecious and flower in the spring (3). The staminate
catkins of pignut hickory are 8 to 18 cm (3 to 7 in) long and develop from axils of leaves of the previous season or from inner scales of the terminal bud
s at the base of the current growth. The pistillate flowers appear in spikes about 6 mm (0.25 in) long on peduncle
s terminating in shoots of the current year. Flowers open from the middle of March in the southeast part of the range to early June in New England
. The catkins usually emerge before the pistillate flowers.
The fruit
of hickory is pear
shaped and enclosed in a thin husk developed from the floral involucre
. The fruit ripens in September and October, and seed
s are dispersed from September through December. Husks are green until maturity; they turn brown to brownish-black as they ripen. The husks become dry at maturity and split away
from the nut
into four valves along sutures. Husks of pignut hickory split only to the middle or slightly beyond and generally cling to the nut, which is unribbed, with a thick shell.
in quantity in 30 years, with optimum production between 75 and 200 years (16). The maximum age for seed production is about 300 years. Good seed crops occur every year or two with light crops in other years; frost
can seriously hinder seed production (22). Usually less than half of the seeds are sound (2,3), but 50 to 75 percent of these will germinate. The hickory shuckworm (Laspeyresia caryana) can seriously reduce germination
. Pignut seed, averaging 440/kg (200/lb), is lighter than the seed of other hickory species. The nuts are disseminated mainly by gravity, but the range of seeding is extended by squirrel
s and chipmunk
s.
and litter
or artificially by stratification
in a moist medium at 1° to 4°C (33° to 40°F) for 30 to 150 days. In forest tree nurseries
unstratified hickory nuts are sown in the fall and stratified nuts are sown in the spring. Hickories are hypogeously
germinating plants, and the nuts seldom remain viable in the forest floor for more than one winter (22).
Seedling growth of hickories is slow. The following height growth of pignut hickory seedlings was reported in the Ohio Valley in the open or under light shade, on red clay
soil (2):
s. Stump sprouting is not as prolific as in other deciduous
trees species but the sprouts that are produced are vigorous and grow fairly rapidly in height. Root sprouts also are vigorous and probably more numerous than stump sprouts in cut-over areas. Small stumps sprout more frequently than large ones. Sprouts that originate at or below ground level and from small stumps are less likely to develop heartwood decay. Pignut hickory is difficult to reproduce from cuttings.
, white oak
, sweet birch (Betula lenta), and American beech
is rated slow. Since hickories constitute 15 percent or less of the basal area of oak
-hickory forest types, most growth and yield information is written in terms of oak rather than oak-hickory. Yields of mixed oak stands (5,7,19) and of hickory stands (2) have been reported. Tree volume tables are available (2,19).
----
¹Second growth.
²Virgin forest.
with few laterals and is rated as windfirm (21). The taproot develops early, which may explain the slow growth of seedling shoots. Taproots may develop in compact and stony soils.
s (including the hickories) are climax
, and the trend of succession
toward this climax is very strong. Although most silvicultural systems when applied to oak types will maintain a hardwood forest, the cutting methods used affects the rapidity with which other species may replace the oaks and hickories (17,18,26).
, which causes stem degrade or loss of volume, or both. Internal discolorations called mineral streak are common and are one major reason why so few standing hickories meet trade specifications. Streaks result from yellow-bellied sapsucker
pecking, pin knots, worm holes, and mechanical injuries. Hickories strongly resist ice damage and seldom develop epicormic branches.
The Index of Plant Diseases in the United States lists 133 fungi and 10 other causes of diseases on Carya species (4,9). Most of the fungi are saprophytes, but a few are damaging to foliage, produce canker
s, or cause trunk
or root
rot
s.
The most common disease of pignut hickory from Pennsylvania southward is a trunk rot caused by Poria spiculosa. Cankers vary in size and appearance depending on their age. A common form develops around a branch wound and resembles a swollen, nearly healed wound. On large trees these may become prominent burl
-like bodies having several vertical or irregular folds in the callus covering. A single trunk canker near the base is a sign that the butt log is badly infected, and multiple cankers are evidence that the entire tree may be a cull.
Major leaf diseases are anthracnose (Gnomonia caryae) and mildew
(Microstroma juglandis). The former causes brown spots with definite margins on the undersides of the leaf. These may coalesce and cause widespread blotching. Mildew invades the leaves and twigs and may form witches' brooms by stimulating bud formation. Although locally prevalent, mildew offers no problem in the management of hickory.
The stem canker
(Nectria galligena) produces depressed areas with concentric bark
rings that develop on the trunk and branches. Affected trees are sometimes eliminated through breakage or competition and sometimes live to reach merchantable size with cull section at the canker. No special control measures are required, but cankered trees should be harvested in stand improvement operations.
A gall-forming fungus species of Phomopsis can produce warty excrescences ranging from small twig gall
s to very large trunk burl
s on northern hickories and oaks. Little information is available on root diseases of hickory.
More than 100 insect
s have been reported to infest hickory trees and wood
products, but only a few cause death or severe damage (1). The hickory bark beetle
(Scolytus quadrispinosus) is the most important insect enemy of hickory, and also one of the most important insect pests of hardwoods in the Eastern United States. During drought
periods in the Southeast, outbreaks often develop and large tracts of timber are killed. At other times, damage may be confined to the killing of a single tree or to portions of the tops of trees. The foliage of heavily infested trees turns red within a few weeks after attack, and the trees soon die. There is one generation per year in northern areas and normally two broods per year in the South. Control consists of felling infested trees and destroying the bark during winter months or storing infested logs in ponds.
Logs and dying trees of several hardwood species including pignut hickory are attacked by the ambrosia beetle
(Platypus quadridentatus) throughout the South and north to West Virginia and North Carolina. The false powderpost beetle
(Xylobiops basilaris) attacks recently felled or dying trees, logs, or limbs with bark in the Eastern and Southern States. Hickory, persimmon (Diospyros virginiana
), and pecan (C. illinoinensis) are most frequently infested, but other hardwoods also are attacked. Healthy trees growing in proximity to heavily infested trees are occasionally attacked but almost always without success. Hickory and persimmon wood (useful in the manufacture of small products such as shuttle blocks, mallet
s, and maul
s) is sometimes seriously damaged.
Hickory is one of several host species of the twig girdler
(Oncideres cingulata). Infested trees and seedlings are not only damaged severely but become ragged and unattractive. A few of the more common species of gall-producing insects attacking hickory are Phylloxera
caryaecaulis, Caryomyia holotricha, C. sanguinolenta, and C. tubicola.
and represent an estimated 10 to 25 percent of their diet. Nuts and flowers are eaten by the wild turkey
and several species of songbird
s. Nuts and bark are eaten by black bear
s, fox
es, rabbit
s, and raccoon
s. Small mammal
s eat the nuts and leaves; 5 to 10 percent of the diet of eastern chipmunk
s is hickory nuts. White-tailed deer
occasionally browse hickory leaves, twig
s, and nuts.
The kernel of hickory seeds is exceptionally high in crude fat
, up to 70 to 80 percent in some species. Crude protein
, phosphorus
, and calcium
contents are generally moderate to low. Crude fiber
is very low.
Pignut hickory makes up a small percentage of the biomass
in low-quality upland hardwood stands that are prime candidates for clearcutting for chips or fuelwood as the first step toward rehabilitation to more productive stands. Hickory has a relatively high heating value and is used extensively as a home heating fuel.
Pignut hickory is an important shade tree
in wooded suburban areas over most of the range but is seldom planted as an ornamental tree.
Carya glabra (Mill.) Sweet var. glabra distinguishes the (typical) pignut hickory from red hickory (C. glabra var. odorata (Marsh.) Little). The taxonomic position of red hickory is controversial. The binomial C. ovalis (Wangenh.) Sarg. was published in 1913 for a segregate of C. glabra. It was reduced to a synonym
of C. glabra in Little's 1953 checklist but was elevated to a variety in the 1979 edition (11). The principal difference is in the husk of the fruit
, opening late and only partly, or remaining closed in C. glabra but promptly splitting
to the base in C. ovalis. However, many trees are intermediate in this trait, and the recorded ranges are almost the same. The leaves of C. ovalis have mostly seven leaflets; those of C. glabra have mostly five leaflets. The two can be distinguished with certainty only in November. Since the two ranges seem to overlap, the distributions have been mapped together as a Carya glabra-ovalis complex (11).
Carya ovalis has also been treated as an interspecific hybrid between C. glabra and C. ovata. C. ovalis was accepted as a polymorphic species especially variable in the size and shape of its nuts and possibly a hybrid. The relationships may be more complex after a long and reticulate phylogeny, according to detailed chemical analyses of hickory nut oils.
One hybrid, C. x demareei Palmer (C. glabra x cordiformis) was described in 1937 from northeastern Arkansas
.
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
-hickory
Hickory
Trees in the genus Carya are commonly known as hickory, derived from the Powhatan language of Virginia. The genus includes 17–19 species of deciduous trees with pinnately compound leaves and big nuts...
forest association in the Eastern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Other common names are pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, and broom hickory. The pear-shaped nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
ripens in September and October and is an important part of the diet of many wild animals. The wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
is used for a variety of products, including fuel for home heating.
Native range
The range of pignut hickory covers nearly all of eastern United States (11). The species grows in central FloridaFlorida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and westward through Louisiana and along the Gulf Coast to Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...
through Mississippi
Mississippi
Mississippi is a U.S. state located in the Southern United States. Jackson is the state capital and largest city. The name of the state derives from the Mississippi River, which flows along its western boundary, whose name comes from the Ojibwe word misi-ziibi...
. It extends through parts of East Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
to Louisiana
Louisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
, Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
, Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
and extreme southeastern Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
. Its range further includes Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
and the southwest corner of New Hampshire
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
westward through southern Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
to central Lower Peninsula of Michigan
Lower Peninsula of Michigan
The Lower Peninsula of Michigan is the southern of the two major landmasses of the U.S. state of Michigan. It is surrounded by water on all sides except its southern border, which it shares with Ohio and Indiana. Geographically, the Lower Peninsula has a recognizable shape that many people...
and Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
.
The best development of this species is in the lower Ohio River
Ohio River
The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...
Basin. It prevails over other species of hickory in the Appalachian forests. Pignut makes up much of the hickory harvested in Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
, West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
, the Cumberland Mountains
Cumberland Mountains
The Cumberland Mountains are a mountain range in the southeastern section of the Appalachian Mountains. They are located in southern West Virginia, western Virginia, eastern edges of Kentucky, and eastern middle Tennessee, including the Crab Orchard Mountains...
of Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
, and the hill country of the Ohio Valley.
Pignut Hickory is also found in Canada in southern Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
. It does however have a limited range and is resticted to the Niagara Peninsula
Niagara Peninsula
The Niagara Peninsula is the portion of Southern Ontario, Canada lying between the south shore of Lake Ontario and the north shore of Lake Erie. It stretches from the Niagara River in the east to Hamilton, Ontario in the west. The population of the peninsula is roughly 1,000,000 people...
, southern Halton Region, the Hamilton
Hamilton, Ontario
Hamilton is a port city in the Canadian province of Ontario. Conceived by George Hamilton when he purchased the Durand farm shortly after the War of 1812, Hamilton has become the centre of a densely populated and industrialized region at the west end of Lake Ontario known as the Golden Horseshoe...
area along western Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
, and southward along the northern shore of Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
and pockets of extreme southwestern Ontario.
Climate
Pignut hickory grows in a humid climateClimate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...
with an average annual precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
of 760 to 2,030 mm (30 to 80 in) of which 510 to 1,020 mm (20 to 40 in) is rain
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
during the growing season. Average snowfall varies from little to none in the South to 2,540 mm (100 in) or more in the mountains of West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
, southeastern New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
, and southern Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
(25).
Within the range of pignut hickory, average annual temperatures vary from 7°C (45°F) in the north to 21°C (70°F) in Florida. Average January temperature varies from -4° to 16°C (25° to 60°F) and average July temperature varies from 21° to 27°C (70° to 80°F). Extremes of 46° and -30°C (115° and -22°F) have been recorded within the range. The growing season
Growing season
In botany, horticulture, and agriculture the growing season is the period of each year when native plants and ornamental plants grow; and when crops can be grown....
varies by latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
and elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
from 140 to 300 days.
Mean annual relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
ranges from 70 to 80 percent with small monthly differences; daytime relative humidity often falls below 50% while nighttime humidity approaches 100%.
Mean annual hours of sunshine
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
range from 2,200 to 3,000. Average January sunshine varies from 100 to 200 hours, and July sunshine from 260 to 340 hours. Mean daily solar radiation ranges from 12.57 to 18.86 million J m± (300 to 450 langleys). In January daily radiation varies from 6.28 to 12.57 million J m± (150 to 300 langleys), and in July from 20.95 to 23.04 million J m± (500 to 550 langleys).
According to one classification of climate (20), the range of pignut hickory south of the Ohio River
Ohio River
The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...
, except for a small area in Florida, is designated as humid, mesothermal
Mesothermal
In climatology, the term mesothermal is used to refer to certain forms of climate found typically in the Earth's Temperate Zones. It has a moderate amount of heat, with winters not cold enough to sustain snow cover...
. That part of the range lying north of the Ohio River is designated humid, mesothermal. Part of the species range in peninsular Florida is classed as subhumid, mesothermal. Mountain
Mountain
Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...
s in Pennsylvania, West Virginia, North Carolina, and Tennessee are classed as wet, microthermal
Microthermal
In climatology, the term microthermal is used to denote the continental climates of Eurasia and North America.The word microthermal is derived from two Greek words meaning "having little heat." This is misleading, however, since the term is intended to describe only the temperature conditions that...
, and mountains in South Carolina and Georgia are classed as wet, mesothermal. Throughout its range, precipitation is rated adequate during all seasons.
Soils and topography
Pignut hickory frequently grows on dry ridgetops and sideslopes throughout its range but it is also common on moist sites, particularly in the mountains and PiedmontPiedmont (United States)
The Piedmont is a plateau region located in the eastern United States between the Atlantic Coastal Plain and the main Appalachian Mountains, stretching from New Jersey in the north to central Alabama in the south. The Piedmont province is a physiographic province of the larger Appalachian division...
. In the Great Smoky Mountains
Great Smoky Mountains
The Great Smoky Mountains are a mountain range rising along the Tennessee–North Carolina border in the southeastern United States. They are a subrange of the Appalachian Mountains, and form part of the Blue Ridge Physiographic Province. The range is sometimes called the Smoky Mountains or the...
pignut hickory has been observed on dry sandy soils at low elevations. Whittaker (27) placed pignut in a submesic class and charted it as ranging up to 1480 m (4,850 ft)-the hickory with the greatest elevational range in the Great Smoky Mountains. In southwest Virginia, south-facing upper slopes from 975 to 1050 m (3,200 to 3,445 ft) of Beanfield Mountain are dominated by pignut hickory, northern red oak Quercus rubra), and white oak (Q. alba). This site is the most xeric habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
on the mountain because of high insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
, 70 percent slopes, and medium- to coarse-textured soils derived from Clinch sandstone. Mid-elevation slopes from 800 to 975 m (2,625 to 3,200 ft) are dominated by chestnut oak (Q. prinus), northern red oak, and pignut hickory and coincide with three shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
formations (12).
The range of pignut hickory encompasses 7 orders
USDA soil taxonomy
USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series.- Example of...
, 12 suborders, and 22 great groups of soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
s (24,25). About two-thirds of the species range is dominated by Ultisols
Ultisols
Ultisols, commonly known as red clay soils, are one of twelve soil orders in the United States Department of Agriculture soil taxonomy. They are defined as mineral soils which contain no calcareous material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer...
, which are low in bases and have subsurface horizons of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
accumulation. They are usually moist but are dry during part of the warm season. Udults is the dominant suborder and Hapludults and Paleudults are the dominant great groups. These soils are derived from a variety of parent materials-sedimentary and metamorphic rocks, glacial till, and in places varying thickness of loess
Loess
Loess is an aeolian sediment formed by the accumulation of wind-blown silt, typically in the 20–50 micrometre size range, twenty percent or less clay and the balance equal parts sand and silt that are loosely cemented by calcium carbonate...
-which vary in age from Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...
to Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
.
A wide range of soil fertility exists as evidenced by soil orders-Alfisols
Alfisols
Alfisols are a soil order in USDA soil taxonomy. Alfisols form in semiarid to humid areas, typically under a hardwood forest cover. They have a clay-enriched subsoil and relatively high native fertility. "Alf" refers to aluminium and iron . Because of their productivity and abundance, the...
and Mollisols
Mollisols
Mollisols are a soil order in USDA soil taxonomy. Mollisols form in semi-arid to semi-humid areas, typically under a grassland cover. They are most commonly found in the mid-latitudes, namely in North America, mostly east of the Rocky Mountains, in South America in Argentina and Brazil, and in...
which are medium to high in base saturation to Ultisols which are low in base saturation (24). Pignut hickory responds to increases in soil nitrogen similarly to American beech (Fagus grandifolia), sugar maple (Acer saccharum), and blackgum (Nyssa sylvatica) (15). These species are rated as intermediate in nitrogen deficiency tolerance and consequently are able to grow with lower levels of nitrogen than are required by "nitrogen- demanding" white ash (Fraxinus americana), yellow-poplar (Liriodendron tulipifera
Liriodendron tulipifera
Liriodendron tulipifera, commonly known as the tulip tree, American tulip tree, tuliptree, tulip poplar or yellow poplar, is the Western Hemisphere representative of the two-species genus Liriodendron, and the tallest eastern hardwood...
), and American basswood (Tilia americana
Tilia americana
Tilia americana is a species of Tilia native to eastern North America, from southeast Manitoba east to New Brunswick, southwest to northeast Texas, and southeast to South Carolina, and west along the Niobrara River to Cherry County, Nebraska...
). Hickories are considered "soil improvers" because their leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
have a relatively high calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
content.
Associated forest cover
Hickories are consistently present in the broad eastern upland climaxClimax vegetation
Climax vegetation is the vegetation which establishes itself on a given site for given climatic conditions in the absence of anthropic action after a long time ....
forest association commonly called oak-hickory, but they are not generally abundant (18). Locally, hickories may make up to 20 to 30 percent of stand basal area, particularly in slope and cove forests below the escarpment
Escarpment
An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...
of the Cumberland Plateau
Cumberland Plateau
The Cumberland Plateau is the southern part of the Appalachian Plateau. It includes much of eastern Kentucky and western West Virginia, part of Tennessee, and a small portion of northern Alabama and northwest Georgia . The terms "Allegheny Plateau" and the "Cumberland Plateau" both refer to the...
(23) and in second-growth forests in the Cumberland Mountains
Cumberland Mountains
The Cumberland Mountains are a mountain range in the southeastern section of the Appalachian Mountains. They are located in southern West Virginia, western Virginia, eastern edges of Kentucky, and eastern middle Tennessee, including the Crab Orchard Mountains...
, especially on benches
Bench (geology)
In geomorphology, geography and geology, a bench or benchland is a long, relatively narrow strip of relatively level or gently inclined land that is bounded by distinctly steeper slopes above and below it...
(14). It has been hypothesized that hickory will replace chestnut (Castanea dentata) killed by the blight (Cryphonectria parasitica) in the Appalachian Highlands (10,12). On Beanfield Mountain in Giles County
Giles County, Virginia
As of the census of 2000, there were 16,657 people, 6,994 households, and 4,888 families residing in the county. The population density was 47 people per square mile . There were 7,732 housing units at an average density of 22 per square mile...
, Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
, the former chestnut-oak complex has changed to an oak-hickory association over a period of 50 years. This association is dominated by pignut hickory with an importance value of 41.0 (maximum value = 300), northern red oak (36.0), and chestnut oak (25.0). White oak, red maple (Acer rubrum), and sugar maple are subdominant species.
Pignut hickory is an associated species in 20 of the 90 forest cover types listed by the Society of American Foresters
Society of American Foresters
The Society of American Foresters is a scientific and educational 501 non-profit organization, representing the forestry profession in the United States of America...
for the eastern United States (6):
Central forest region
40 Post OakPost oak
Quercus stellata is an oak in the white oak group. It is a small tree, typically 10–15 m tall and 30–60 cm trunk diameter, though occasional specimens reach 30 m tall and 140 cm diameter. It is native to the eastern United States, from Connecticut in the northeast, west to southern Iowa, southwest...
-Blackjack Oak
Blackjack oak
Quercus marilandica is a small oak, one of the red oak group Quercus sect. Lobatae, but fairly isolated from the others...
44 Chestnut Oak
Chestnut oak
Quercus prinus , the chestnut oak, is a species of oak in the white oak group, Quercus sect. Quercus. It is native to the eastern United States, where it is one of the most important ridgetop trees from southern Maine southwest to central Mississippi, with an outlying northwestern population in...
45 Pitch Pine
Pitch Pine
The Pitch Pine, Pinus rigida, is a small-to-medium sized pine, native to eastern North America. This species occasionally hybridizes with other pine species such as Loblolly Pine , Shortleaf Pine , and Pond Pine The Pitch Pine, Pinus rigida, is a small-to-medium sized (6-30 meters or 20-100 feet)...
46 Eastern Redcedar
52 White Oak-Black Oak-Northern Red Oak
Northern Red Oak
Quercus rubra, commonly called northern red oak or champion oak, , is an oak in the red oak group . It is a native of North America, in the northeastern United States and southeast Canada...
53 White Oak
55 Northern Red Oak
57 Yellow-Poplar
59 Yellow-Poplar-White Oak-Northern Red Oak
64 Sassafras
Sassafras
Sassafras is a genus of three extant and one extinct species of deciduous trees in the family Lauraceae, native to eastern North America and eastern Asia.-Overview:...
-Persimmon
Persimmon
A persimmon is the edible fruit of a number of species of trees in the genus Diospyros in the ebony wood family . The word Diospyros means "the fire of Zeus" in ancient Greek. As a tree, it is a perennial plant...
110 Black Oak
Southern forest region
75 Shortleaf PineShortleaf Pine
Pinus echinata is a species of pine native to the eastern United States from southern New York south to northern Florida, west to the extreme southeast of Kansas, and southwest to eastern Texas. The tree is variable in form, sometimes straight, sometimes crooked, with an irregular crown...
76 Shortleaf Pine-Oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
78 Virginia Pine
Virginia Pine
Pinus virginiana is a medium-sized tree, often found on poorer soils from Long Island in southern New York south through the Appalachian Mountains to western Tennessee and Alabama. The usual size range for this pine is 9–18 m, but can grow taller under optimum conditions. The trunk can be...
-Oak
79 Virginia Pine
80 Loblolly Pine
Loblolly Pine
Pinus taeda is one of several pines native to the Southeastern United States, from central Texas east to Florida, and north to Delaware. It is particularly dominant in the eastern half of North Carolina, where there are huge expanses consisting solely of Loblolly Pine trees...
-Shortleaf Pine
Shortleaf Pine
Pinus echinata is a species of pine native to the eastern United States from southern New York south to northern Florida, west to the extreme southeast of Kansas, and southwest to eastern Texas. The tree is variable in form, sometimes straight, sometimes crooked, with an irregular crown...
81 Loblolly Pine
82 Loblolly Pine-Hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
83 Longleaf Pine-Slash Pine
Slash Pine
Pinus elliottii, commonly known as the Slash Pine, is a pine native to the southeastern United States, from southern South Carolina west to southeastern Louisiana, and south to the Florida Keys....
Because the range of pignut hickory is so extensive, it is not feasible to list the associated tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s, herb
Herbaceous
A herbaceous plant is a plant that has leaves and stems that die down at the end of the growing season to the soil level. They have no persistent woody stem above ground...
s, and grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
es, which vary according to elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
, topographic conditions, edaphic
Edaphic
Edaphic is a nature related to soil. Edaphic qualities may characterize the soil itself, including drainage, texture, or chemical properties such as pH. Edaphic may also characterize organisms, such as plant communities, where it specifies their relationships with soil...
features, and geographic locality.
Reproduction and early growth
Flowering and FruitFruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
ing- Hickories are monoecious and flower in the spring (3). The staminate
Stamen
The stamen is the pollen producing reproductive organ of a flower...
catkins of pignut hickory are 8 to 18 cm (3 to 7 in) long and develop from axils of leaves of the previous season or from inner scales of the terminal bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s at the base of the current growth. The pistillate flowers appear in spikes about 6 mm (0.25 in) long on peduncle
Peduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...
s terminating in shoots of the current year. Flowers open from the middle of March in the southeast part of the range to early June in New England
New England
New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...
. The catkins usually emerge before the pistillate flowers.
The fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
of hickory is pear
Pear
The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....
shaped and enclosed in a thin husk developed from the floral involucre
Involucre
Involucre may refer to* involucral bract, a bract, bract pair, or whorl of bracts surrounding a flower or inflorescence* a term sometimes misused for the cupule surrounding developing nuts in the Fagaceae...
. The fruit ripens in September and October, and seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s are dispersed from September through December. Husks are green until maturity; they turn brown to brownish-black as they ripen. The husks become dry at maturity and split away
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...
from the nut
Nut (fruit)
A nut is a hard-shelled fruit of some plants having an indehiscent seed. While a wide variety of dried seeds and fruits are called nuts in English, only a certain number of them are considered by biologists to be true nuts...
into four valves along sutures. Husks of pignut hickory split only to the middle or slightly beyond and generally cling to the nut, which is unribbed, with a thick shell.
Seed production and dissemination
Pignut hickory begins to bear seedSeed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
in quantity in 30 years, with optimum production between 75 and 200 years (16). The maximum age for seed production is about 300 years. Good seed crops occur every year or two with light crops in other years; frost
Frost
Frost is the solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air as well as below the freezing point of water. Frost crystals' size differ depending on time and water vapour available. Frost is also usually...
can seriously hinder seed production (22). Usually less than half of the seeds are sound (2,3), but 50 to 75 percent of these will germinate. The hickory shuckworm (Laspeyresia caryana) can seriously reduce germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
. Pignut seed, averaging 440/kg (200/lb), is lighter than the seed of other hickory species. The nuts are disseminated mainly by gravity, but the range of seeding is extended by squirrel
Squirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
s and chipmunk
Chipmunk
Chipmunks are small striped squirrels native to North America and Asia. They are usually classed either as a single genus with three subgenera, or as three genera.-Etymology and taxonomy:...
s.
Seedling development
Hickories exhibit embryo dormancy which is overcome naturally by overwintering in the duffForest floor
The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stages of decomposition above the soil surface...
and litter
Plant litter
Plant litter, leaf litter or tree litter is dead plant material, such as leaves, bark, needles, and twigs, that has fallen to the ground. Litter provides habitat for small animals, fungi, and plants, and the material may be used to construct nests. As litter decomposes, nutrients are released to...
or artificially by stratification
Stratification (botany)
In horticulture, stratification is the process of pretreating seeds to simulate natural winter conditions that a seed must endure before germination. Many seed species undergo an embryonic dormancy phase, and generally will not sprout until this dormancy is broken...
in a moist medium at 1° to 4°C (33° to 40°F) for 30 to 150 days. In forest tree nurseries
Nursery (horticulture)
A nursery is a place where plants are propagated and grown to usable size. They include retail nurseries which sell to the general public, wholesale nurseries which sell only to businesses such as other nurseries and to commercial gardeners, and private nurseries which supply the needs of...
unstratified hickory nuts are sown in the fall and stratified nuts are sown in the spring. Hickories are hypogeously
Hypogeal
Hypogeal means "underground".* In botany, a seed is described as hypogeal when the cotyledons of the germinating seed remain non-photosynthetic, inside the seed shell, and below ground...
germinating plants, and the nuts seldom remain viable in the forest floor for more than one winter (22).
Seedling growth of hickories is slow. The following height growth of pignut hickory seedlings was reported in the Ohio Valley in the open or under light shade, on red clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
soil (2):
| Age | Height | |
|---|---|---|
| (yr) | (cm) | (in) |
| 1 | 8 | 3.0 |
| 2 | 15 | 5.8 |
| 3 | 20 | 8.0 |
| 4 | 30 | 12.0 |
| 5 | 43 | 17.0 |
Vegetative reproduction
Hickories sprout readily from stumps and rootRoot
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s. Stump sprouting is not as prolific as in other deciduous
Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...
trees species but the sprouts that are produced are vigorous and grow fairly rapidly in height. Root sprouts also are vigorous and probably more numerous than stump sprouts in cut-over areas. Small stumps sprout more frequently than large ones. Sprouts that originate at or below ground level and from small stumps are less likely to develop heartwood decay. Pignut hickory is difficult to reproduce from cuttings.
Sapling and pole stages to maturity
Growth and Yield- Pignut hickory often grows 24 to 27 m (80 to 90 ft) tall and occasionally reaches 37 m (120 ft), with d.b.h. of 91 to 122 cm (36 to 48 in). The bole is often forked. Height and diameter by age are shown in table 1 for selected locations. Diameter growth of pignut hickory (along with chestnut oakChestnut oak
Quercus prinus , the chestnut oak, is a species of oak in the white oak group, Quercus sect. Quercus. It is native to the eastern United States, where it is one of the most important ridgetop trees from southern Maine southwest to central Mississippi, with an outlying northwestern population in...
, white oak
White oak
Quercus alba, the white oak, is one of the pre-eminent hardwoods of eastern North America. It is a long-lived oak of the Fagaceae family, native to eastern North America and found from southern Quebec west to eastern Minnesota and south to northern Florida and eastern Texas. Specimens have been...
, sweet birch (Betula lenta), and American beech
American Beech
Fagus grandifolia, also known as American Beech or North american beech, is a species of beech native to eastern North America, from Nova Scotia west to southern Ontario in southeastern Canada, west to Wisconsin and south to eastern Texas and northern Florida in the United States. Trees in the...
is rated slow. Since hickories constitute 15 percent or less of the basal area of oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
-hickory forest types, most growth and yield information is written in terms of oak rather than oak-hickory. Yields of mixed oak stands (5,7,19) and of hickory stands (2) have been reported. Tree volume tables are available (2,19).
| Age | D.b.h. | Height | |||
|---|---|---|---|---|---|
| S. Indiana and N.Kentucky¹ | Ohio Valley¹ | Northern Ohio¹ | Cumberland Mountains² | Mississippi Valley² | |
| (yr) | (cm) | (m) | (m) | (m) | (m) |
| 10 | 2 | 2.7 | 2.1 | 1.8 | 1.8 |
| 20 | 5 | 5.8 | 6.1 | 4.3 | 5.8 |
| 30 | 8 | 9.8 | 10.7 | 7.3 | 8.2 |
| 40 | 11 | 12.8 | 14.6 | 9.8 | 10.4 |
| 50 | 14 | 15.5 | 18.6 | 12.2 | 12.2 |
| 60 | 17 | 17.7 | 21.0 | 14.6 | 14.0 |
| 70 | 21 | 19.5 | 22.6 | 16.8 | 15.8 |
| 80 | 25 | 21.0 | -- | 18.9 | 17.7 |
| (yr) | (in) | (ft) | (ft) | (ft) | (ft) |
| 10 | 1.0 | 9 | 7 | 6 | 6 |
| 20 | 2.0 | 19 | 20 | 14 | 19 |
| 30 | 3.2 | 32 | 35 | 24 | 27 |
| 40 | 4.4 | 42 | 48 | 32 | 34 |
| 50 | 5.5 | 51 | 61 | 40 | 40 |
| 60 | 6.8 | 58 | 69 | 48 | 46 |
| 70 | 8.4 | 64 | 74 | 55 | 52 |
| 80 | 10.0 | 69 | -- | 62 | 58 |
----
¹Second growth.
²Virgin forest.
Rooting habit
Pignut hickory tends to develop a pronounced taprootTaproot
A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...
with few laterals and is rated as windfirm (21). The taproot develops early, which may explain the slow growth of seedling shoots. Taproots may develop in compact and stony soils.
Reaction to competition
The hickories as a group are classed as intermediate in shade tolerance; however, pignut hickory has been classed as intolerant in the Northeast and tolerant in the Southeast. In much of the area covered by mixed oak forests, shade-tolerant hardwoodHardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
s (including the hickories) are climax
Climax vegetation
Climax vegetation is the vegetation which establishes itself on a given site for given climatic conditions in the absence of anthropic action after a long time ....
, and the trend of succession
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...
toward this climax is very strong. Although most silvicultural systems when applied to oak types will maintain a hardwood forest, the cutting methods used affects the rapidity with which other species may replace the oaks and hickories (17,18,26).
Damaging agents
Pignut hickory is easily damaged by fireWildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
, which causes stem degrade or loss of volume, or both. Internal discolorations called mineral streak are common and are one major reason why so few standing hickories meet trade specifications. Streaks result from yellow-bellied sapsucker
Yellow-bellied Sapsucker
The Yellow-bellied Sapsucker is a medium-sized woodpecker found in North America, Central America and the Caribbean.-Taxonomy:...
pecking, pin knots, worm holes, and mechanical injuries. Hickories strongly resist ice damage and seldom develop epicormic branches.
The Index of Plant Diseases in the United States lists 133 fungi and 10 other causes of diseases on Carya species (4,9). Most of the fungi are saprophytes, but a few are damaging to foliage, produce canker
Canker
Canker and anthracnose are general terms for a large number of different plant diseases, characterised by broadly similar symptoms including the appearance of small areas of dead tissue, which grow slowly, often over a period of years. Some are of only minor consequence, but others are ultimately...
s, or cause trunk
Trunk (botany)
In botany, trunk refers to the main wooden axis of a tree that supports the branches and is supported by and directly attached to the roots. The trunk is covered by the bark, which is an important diagnostic feature in tree identification, and which often differs markedly from the bottom of the...
or root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
rot
Dry rot
Dry rot refers to a type of wood decay caused by certain types of fungi, also known as True Dry Rot, that digests parts of the wood which give the wood strength and stiffness...
s.
The most common disease of pignut hickory from Pennsylvania southward is a trunk rot caused by Poria spiculosa. Cankers vary in size and appearance depending on their age. A common form develops around a branch wound and resembles a swollen, nearly healed wound. On large trees these may become prominent burl
Burl
A burl or bur or burr is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.A burl results from a tree undergoing some form of stress. It may be caused...
-like bodies having several vertical or irregular folds in the callus covering. A single trunk canker near the base is a sign that the butt log is badly infected, and multiple cankers are evidence that the entire tree may be a cull.
Major leaf diseases are anthracnose (Gnomonia caryae) and mildew
Mildew
Mildew refers to certain kinds of molds or fungi.In Old English, it meant honeydew , and later came to mean mildew in the modern sense of mold or fungus....
(Microstroma juglandis). The former causes brown spots with definite margins on the undersides of the leaf. These may coalesce and cause widespread blotching. Mildew invades the leaves and twigs and may form witches' brooms by stimulating bud formation. Although locally prevalent, mildew offers no problem in the management of hickory.
The stem canker
Canker
Canker and anthracnose are general terms for a large number of different plant diseases, characterised by broadly similar symptoms including the appearance of small areas of dead tissue, which grow slowly, often over a period of years. Some are of only minor consequence, but others are ultimately...
(Nectria galligena) produces depressed areas with concentric bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
rings that develop on the trunk and branches. Affected trees are sometimes eliminated through breakage or competition and sometimes live to reach merchantable size with cull section at the canker. No special control measures are required, but cankered trees should be harvested in stand improvement operations.
A gall-forming fungus species of Phomopsis can produce warty excrescences ranging from small twig gall
Gall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
s to very large trunk burl
Burl
A burl or bur or burr is a tree growth in which the grain has grown in a deformed manner. It is commonly found in the form of a rounded outgrowth on a tree trunk or branch that is filled with small knots from dormant buds.A burl results from a tree undergoing some form of stress. It may be caused...
s on northern hickories and oaks. Little information is available on root diseases of hickory.
More than 100 insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s have been reported to infest hickory trees and wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
products, but only a few cause death or severe damage (1). The hickory bark beetle
Bark beetle
A bark beetle is one of approximately 220 genera with 6,000 species of beetles in the subfamily Scolytinae. Traditionally, this was considered a distinct family Scolytidae, but now it is understood that bark beetles are in fact very specialized members of the "true weevil" family...
(Scolytus quadrispinosus) is the most important insect enemy of hickory, and also one of the most important insect pests of hardwoods in the Eastern United States. During drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
periods in the Southeast, outbreaks often develop and large tracts of timber are killed. At other times, damage may be confined to the killing of a single tree or to portions of the tops of trees. The foliage of heavily infested trees turns red within a few weeks after attack, and the trees soon die. There is one generation per year in northern areas and normally two broods per year in the South. Control consists of felling infested trees and destroying the bark during winter months or storing infested logs in ponds.
Logs and dying trees of several hardwood species including pignut hickory are attacked by the ambrosia beetle
Ambrosia beetle
Ambrosia beetles are beetles of the weevil subfamilies Scolytinae and Platypodinae , which live in nutritional symbiosis with ambrosia fungi and probably with bacteria...
(Platypus quadridentatus) throughout the South and north to West Virginia and North Carolina. The false powderpost beetle
Bostrichidae
The Bostrichidae are a family of beetles with more than 700 described species. They are commonly called auger beetles, false powderpost beetles or horned powderpost beetles. The head of most auger beetles cannot be seen from above, as it is downwardly directed and hidden by the thorax...
(Xylobiops basilaris) attacks recently felled or dying trees, logs, or limbs with bark in the Eastern and Southern States. Hickory, persimmon (Diospyros virginiana
Diospyros virginiana
Diospyros virginiana, commonly called the American persimmon, common persimmon, Eastern persimmon, "'simmon" and "possumwood", is a persimmon species known by a variety of names including. It ranges from New England to Florida, and west to Texas, Louisiana, Oklahoma, and Kansas...
), and pecan (C. illinoinensis) are most frequently infested, but other hardwoods also are attacked. Healthy trees growing in proximity to heavily infested trees are occasionally attacked but almost always without success. Hickory and persimmon wood (useful in the manufacture of small products such as shuttle blocks, mallet
Mallet
A mallet is a kind of hammer, usually of rubber,or sometimes wood smaller than a maul or beetle and usually with a relatively large head.-Tools:Tool mallets come in different types, the most common of which are:...
s, and maul
Maul
A splitting maul also known as a block buster, or block splitter is a heavy, long-handled hammer used for splitting a piece of wood along its grain. One side of its head is like a sledgehammer, and the other side is like an axe.- Wedged mauls :...
s) is sometimes seriously damaged.
Hickory is one of several host species of the twig girdler
Longhorn beetle
The longhorn beetles are a cosmopolitan family of beetles, typically characterized by extremely long antennae, which are often as long as or longer than the beetle's body...
(Oncideres cingulata). Infested trees and seedlings are not only damaged severely but become ragged and unattractive. A few of the more common species of gall-producing insects attacking hickory are Phylloxera
Phylloxera
Grape phylloxera ; originally described in France as Phylloxera vastatrix; equated to the previously described Daktulosphaira vitifoliae, Phylloxera vitifoliae; commonly just called phylloxera is a pest of commercial grapevines worldwide, originally native to eastern North America...
caryaecaulis, Caryomyia holotricha, C. sanguinolenta, and C. tubicola.
Special uses
Hickories provide food to many kinds of wildlife (8,13). The nuts are relished by several species of squirrelSquirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
and represent an estimated 10 to 25 percent of their diet. Nuts and flowers are eaten by the wild turkey
Wild Turkey
The Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is the same species as the domestic turkey, which derives from the South Mexican subspecies of wild turkey .Adult wild turkeys have long reddish-yellow to grayish-green...
and several species of songbird
Songbird
A songbird is a bird belonging to the suborder Passeri of the perching birds . Another name that is sometimes seen as scientific or vernacular name is Oscines, from Latin oscen, "a songbird"...
s. Nuts and bark are eaten by black bear
American black bear
The American black bear is a medium-sized bear native to North America. It is the continent's smallest and most common bear species. Black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in...
s, fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s, and raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
s. Small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s eat the nuts and leaves; 5 to 10 percent of the diet of eastern chipmunk
Chipmunk
Chipmunks are small striped squirrels native to North America and Asia. They are usually classed either as a single genus with three subgenera, or as three genera.-Etymology and taxonomy:...
s is hickory nuts. White-tailed deer
White-tailed Deer
The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru...
occasionally browse hickory leaves, twig
Twig
A twig is a small thin terminal branch of a woody plant. Twigs are critically important in identification of trees, shrubs and vines, especially in wintertime. The buds on the twig are an important diagnostic characteristic, as are the abscission scars where the leaves have fallen away...
s, and nuts.
The kernel of hickory seeds is exceptionally high in crude fat
Fat
Fats consist of a wide group of compounds that are generally soluble in organic solvents and generally insoluble in water. Chemically, fats are triglycerides, triesters of glycerol and any of several fatty acids. Fats may be either solid or liquid at room temperature, depending on their structure...
, up to 70 to 80 percent in some species. Crude protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
, and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
contents are generally moderate to low. Crude fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...
is very low.
Pignut hickory makes up a small percentage of the biomass
Biomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
in low-quality upland hardwood stands that are prime candidates for clearcutting for chips or fuelwood as the first step toward rehabilitation to more productive stands. Hickory has a relatively high heating value and is used extensively as a home heating fuel.
Pignut hickory is an important shade tree
Shade tree
A shade tree is any tree grown specifically for its shade. This term usually applies to large trees with spreading canopies. Shade trees are effective in reducing the energy used in cooling homes....
in wooded suburban areas over most of the range but is seldom planted as an ornamental tree.
Genetics
Carya glabra var. megacarpa (Sarg.) Sarg., coast pignut hickory, was once recognized as a distinct variety but is now considered to be a synonym of C. glabra (Mill.) Sweet. C. leiodermis Sarg., swamp hickory, has also been added as a synonym of C. glabra (11).Carya glabra (Mill.) Sweet var. glabra distinguishes the (typical) pignut hickory from red hickory (C. glabra var. odorata (Marsh.) Little). The taxonomic position of red hickory is controversial. The binomial C. ovalis (Wangenh.) Sarg. was published in 1913 for a segregate of C. glabra. It was reduced to a synonym
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
of C. glabra in Little's 1953 checklist but was elevated to a variety in the 1979 edition (11). The principal difference is in the husk of the fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
, opening late and only partly, or remaining closed in C. glabra but promptly splitting
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...
to the base in C. ovalis. However, many trees are intermediate in this trait, and the recorded ranges are almost the same. The leaves of C. ovalis have mostly seven leaflets; those of C. glabra have mostly five leaflets. The two can be distinguished with certainty only in November. Since the two ranges seem to overlap, the distributions have been mapped together as a Carya glabra-ovalis complex (11).
Carya ovalis has also been treated as an interspecific hybrid between C. glabra and C. ovata. C. ovalis was accepted as a polymorphic species especially variable in the size and shape of its nuts and possibly a hybrid. The relationships may be more complex after a long and reticulate phylogeny, according to detailed chemical analyses of hickory nut oils.
One hybrid, C. x demareei Palmer (C. glabra x cordiformis) was described in 1937 from northeastern Arkansas
Arkansas
Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...
.