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''Quercus macrocarpa'', the bur oak or burr oak, is a species of
oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...
tree native to eastern North America. It is in the
white oak The genus ''Quercus'' contains about 500 species, some of which are listed here. The genus, as is the case with many large genera, is divided into subgenera and sections. Traditionally, the genus ''Quercus'' was divided into the two subgenera '' ...
section, ''Quercus'' sect. ''Quercus'', and is also called mossycup oak, mossycup white oak, blue oak, or scrub oak. The acorns are the largest of any North American oak (thus the species name ''macrocarpa'', from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
"large" and "fruit"), and are important food for wildlife.


Description

''Quercus macrocarpa'' is a large
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
growing up to , rarely , in height, and is one of the most massive oaks with a trunk diameter of up to ; reports of taller trees occur, but have not been verified. It is one of the slowest-growing oaks, with a growth rate of per year when young. However, one source states that a well-established tree can grow up to per year. A 20-year-old tree will be about tall if grown in full sun. Naturally occurring saplings in forests will typically be older. Bur oaks commonly get to be 200 to 300 years old, and may live up to 400 years. The bark is gray with distinct vertical ridges. The
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
are long and broad, variable in shape, with a lobed margin. Most often, the basal two-thirds is narrower and deeply lobed, while the apical third is wider and has shallow lobes or large teeth. They usually do not show strong fall color, although fine golden hues are occasionally seen. The
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s are greenish-yellow
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in ''Salix''). They contain many, usually unisexual flowers, arranged cl ...
s, produced in the spring. The
acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera ''Quercus'' and '' Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and borne ...
s are very large, long and broad, having a large cup that wraps much of the way around the nut, with large overlapping scales and often a fringe at the edge of the cup. The wood when sawn transversely shows the characteristic annual rings formed by secondary thickening. Bur oak is sometimes confused with other members of the white oak section, such as ''
Quercus bicolor ''Quercus bicolor'', the swamp white oak, is a North American species of medium-sized trees in the beech family. It is a common element of America's north central and northeastern mixed forests. It can survive in a variety of habitats. It forms ...
'' (swamp white oak), ''
Quercus lyrata ''Quercus lyrata'', the overcup oak, is an oak in the white oak group (''Quercus'' sect. ''Quercus''). The common name, overcup oak, refers to its acorns that are mostly enclosed within the acorn cup. It is native to lowland wetlands in the eas ...
'' (overcup oak), and ''
Quercus alba An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' ...
'' (white oak). It hybridises with several other species of oaks.


Varieties

Two
varieties Variety may refer to: Arts and entertainment Entertainment formats * Variety (radio) * Variety show, in theater and television Films * ''Variety'' (1925 film), a German silent film directed by Ewald Andre Dupont * ''Variety'' (1935 film), ...
are accepted in
Kew Kew () is a district in the London Borough of Richmond upon Thames. Its population at the 2011 census was 11,436. Kew is the location of the Royal Botanic Gardens ("Kew Gardens"), now a World Heritage Site, which includes Kew Palace. Kew is a ...
's
Plants of the World Online Plants of the World Online (POWO) is an online database published by the Royal Botanic Gardens, Kew. It was launched in March 2017 with the ultimate aim being "to enable users to access information on all the world's known seed-bearing plants by ...
: *''Quercus macrocarpa'' var. ''macrocarpa'' *''Quercus macrocarpa'' var. ''depressa''


Distribution and habitat

''Quercus macrocarpa'' is widespread in the Atlantic coastal plain from
New Brunswick New Brunswick (french: Nouveau-Brunswick, , locally ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. It is the only province with both English and ...
to
North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
, west as far as
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
, eastern
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
,
Wyoming Wyoming () is a U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the south ...
, and northeastern
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...
. The vast majority of the populations are found in the eastern
Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...
, the
Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...
Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...
Ohio Valley The Ohio River is a long river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing southwesterly from western Pennsylvania to its mouth on the Mississippi River at the southern tip of Illinoi ...
, and the
Great Lakes region The Great Lakes region of North America is a binational Canadian–American region that includes portions of the eight U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin along with the Canadian p ...
. Bur oaks primarily grow in a
temperate climate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
on the western oak–hickory forested regions in the United States and into Canada. It commonly grows in the open, away from dense
forest A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
canopy. For this reason, it is an important tree on the eastern
prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
s, often found near
waterway A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. A first distinction is necessary b ...
s in otherwise more forested areas, where there is a break in the canopy. It is
drought resistant Drought tolerance is the ability to which a plant maintains its biomass production during arid or drought conditions. Some plants are naturally adapted to dry conditions'','' surviving with protection mechanisms such as desiccation tolerance, deto ...
, possibly because of its long
taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproo ...
. At the end of the growing season, a one-year sapling may have a taproot deep and a lateral root spread of . The
West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...
state champion bur oak has a trunk diameter of almost . Large bur oaks, older than 12 years, are fire-tolerant because of their thick bark. One of the bur oak's most common habitats, especially in Midwestern United States, is the
oak savanna An oak savanna is a type of savanna—or lightly forested grassland—where oaks (''Quercus ''spp.) are the dominant trees. The terms "oakery" or "woodlands" are also used commonly, though the former is more prevalent when referencing the Mediter ...
, where fires often occurred in early spring or late fall. Without fires, bur oak is often succeeded by other tree and shrub species that are more shade-tolerant. Older bur oaks may survive in dense woodlands for 80 years, until they are weakened by wood-rot fungi in the lower branches killed by shade, and by 100 to 110 years, they are often snapped by wind storms.


Ecology

The acorns are the largest of any North American oak and are an important
wildlife Wildlife refers to domestication, undomesticated animal species (biology), species, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introduced by humans. Wildlife was also synonymous ...
food;
American black bear The American black bear (''Ursus americanus''), also called simply a black bear or sometimes a baribal, is a medium-sized bear endemic to North America. It is the continent's smallest and most widely distributed bear species. American black bear ...
s sometimes tear off branches to get them. However, heavy nut crops are borne only every few years. In this evolutionary strategy, known as
masting Mast is the fruit of forest trees and shrubs, such as acorns and other nuts. The term derives from the Old English ''mæst'', meaning the nuts of forest trees that have accumulated on the ground, especially those used historically for fattening do ...
, the large seed crop every few years overwhelms the ability of seed predators to eat the acorns, thus ensuring the survival of some seeds. Other wildlife, such as
deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...
and
porcupine Porcupines are large rodents with coats of sharp spines, or quills, that protect them against predation. The term covers two families of animals: the Old World porcupines of family Hystricidae, and the New World porcupines of family, Erethizont ...
, eat the leaves, twigs and bark.
Cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
are heavy browsers in some areas. The bur oak is the only known foodplant of '' Bucculatrix recognita''
caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...
s. Many species of arthropods form
gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths of plant tissues, similar to be ...
s on the leaves and twigs, including '' Aceria querci'' (a
mite Mites are small arachnids (eight-legged arthropods). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari, but genetic analysis does not show clear evid ...
) and numerous cynipid wasps: '' Acraspis macrocarpae'', '' Acraspis villosa'', '' Andricus chinquapin'', '' Andricus dimorphus'', '' Andricus foliaformis'', ''
Andricus flavohirtus ''Andricus'' is a genus of oak gall wasps in the family Cynipidae. Life cycle As in all Hymenoptera, sex-determination in species of the genus ''Andricus'' is governed by haplodiploidy: males develop from unfertilized eggs and are haploid, an ...
'', '' Andricus quercuspetiolicola'', ''
Callirhytis flavipes ''Callirhytis'' is a genus of gall wasps in the family Cynipidae Gall wasps, also incorrectly called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce ...
'', '' Disholcaspis quercusmamma'', '' Neuroterus floccosus'', '' Neuroterus saltarius'', ''
Neuroterus umbilicatus ''Neuroterus'' is a genus of gall wasps that induce galls on oaks in which the wasp larvae live and feed. Some species produce galls that fall off the host plant and 'jump' along the ground due to the movement of the larvae within. ''Neuroteru ...
'', '' Philonix nigra'', and ''
Phylloteras poculum ''Phylloteras'' is a North America, North American genus of gall wasp, gall wasps in the family (biology), family Cynipidae, Tribe (biology), tribe Cynipini (oak gall wasps). Species There are at least 4 described species in ''Phylloteras'', p ...
''.


Diseases

Bur oak blight Bur oak blight (BOB) is a fungal disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are ...
is caused by a fungal pathogen '' Tubakia iowensis''. It forms black pustules on the petioles and causes leaf discoloration and death, making the tree more susceptible to other secondary issues such as ''Armillaria'' root rot or '' Agrilus bilineatus'' (two-lined chestnut borer).


Cultivation

''Quercus macrocarpa'' is cultivated by
plant nurseries A nursery is a place where plants are propagated and grown to a desired size. Mostly the plants concerned are for gardening, forestry or conservation biology, rather than agriculture. They include retail nurseries, which sell to the general p ...
for use in gardens, in parks, and on urban sidewalks. Among the white oaks, it is one of the most tolerant of
urban Urban means "related to a city". In that sense, the term may refer to: * Urban area, geographical area distinct from rural areas * Urban culture, the culture of towns and cities Urban may also refer to: General * Urban (name), a list of people ...
conditions, and is one of the fastest-growing of the group. It has been planted in many climates, ranging northwards to
Anchorage Anchorage () is the largest city in the U.S. state of Alaska by population. With a population of 291,247 in 2020, it contains nearly 40% of the state's population. The Anchorage metropolitan area, which includes Anchorage and the neighboring Ma ...
,
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...
, and as far south as
Mission, Texas Mission is a city in Hidalgo County, Texas, United States. Its population was 77,058 at the 2010 census and an estimated 84,331 in 2019. Mission is part of the McAllen–Edinburg–Mission and Reynosa–McAllen metropolitan areas. Geography M ...
. It withstands chinook conditions in
Calgary Calgary ( ) is the largest city in the western Canadian province of Alberta and the largest metro area of the three Prairie Provinces. As of 2021, the city proper had a population of 1,306,784 and a metropolitan population of 1,481,806, makin ...
,
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
. It is drought tolerant.
Coppicing Coppicing is a traditional method of woodland management Forest management is a branch of forestry concerned with overall administrative, legal, economic, and social aspects, as well as scientific and technical aspects, such as silviculture, pro ...
has been shown to produce superior growth.


Uses

The wood of ''Quercus macrocarpa'' is commercially valuable; it is durable, used for flooring, fence posts, cabinets, and barrels. The acorns can be eaten boiled and raw. Native Americans have used the astringent bark to treat wounds, sores, rashes, and diarrhea.


Culture

Many places are named after the burr oak, such as
Burr Oak State Park Burr Oak State Park is a public recreation area located northeast of Glouster, Ohio, Glouster in the U.S. state of Ohio. The park sits mostly in Morgan County, Ohio, Morgan County, with part extending into Athens County, Ohio, Athens County. The ...
in
Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...
, the cities of
Burr Oak, Iowa Burr Oak is an unincorporated community in Winneshiek County, Iowa, United States, very close to the Minnesota state line. Burr Oak is a census-designated place and the population was 166 in the 2010 census. History Burr Oak was platted in 1 ...
and Burr Oak, Kansas, and the village of Burr Oak, Michigan. ''Burr Oaks'' (1947) is a volume of poetry by
Richard Eberhart Richard Ghormley Eberhart (April 5, 1904 – June 9, 2005) was an American poet who published more than a dozen books of poetry and approximately twenty works in total. "Richard Eberhart emerged out of the 1930s as a modern stylist with romanti ...
.


References


Further reading

* {{Taxonbar, from=Q1082365
macrocarpa ''Hesperocyparis macrocarpa'' is a coniferous tree. It is commonly known as the Monterey cypress and is one of several species of cypress trees endemic to California. The Monterey cypress is found naturally only on the Central Coast of Califo ...
Trees of Canada Trees of the United States Taxa named by André Michaux Plants described in 1801 Plants used in traditional Native American medicine