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| ## bur oak {#bur-oak .Title-Header}                                   |
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| *Quercus macrocarpa* Michx.                                           |
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| Plant Symbol = QUMA2                                                  |
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Contributed by: USDA NRCS National Plant Data Center & the Biota of
North America Program

### 

## Alternate Names

Blue oak, mossycup oak, mossy-overcup oak

## Uses 

*Industry*: Bur oak wood is used for cabinetry, barrels, hardwood
flooring, and fence posts. Main sources of trees for timber are Iowa and
Illinois bottomlands. The wood is sometimes marketed as 'white oak.'

*Ethnobotanic*: Native Americans made a bark decoction with astringent
properties used to treat diarrhea, wounds and sores, hemorrhoids, poison
oak, and insect bites. The large, sweet acorns have been eaten boiled
and raw.

*Wildlife*: The acorns are eaten by many birds and mammals, including
squirrels, rabbits, ground squirrels, mice, deer, wood ducks, and blue
jays. They are dispersed by rodents and blue jays, which frequently
cache the acorns for later use. The foliage is eaten by deer and cattle.
Red-tailed hawks, screech owls, fox squirrels, and flying squirrels nest
in large trees of bur oak.

*Conservation*: Bur oak is tolerant of city smoke and other air
pollutants and of soils that are compacted, sandy, and/or of high pH --
it is commonly planted as a shade tree in many urban areas of the United
States. The trees become large and are suited for lawns and other open
areas, including golf courses, parks, large

islands, and fields. They also are useful in rehabilitation of degraded
sites and have been widely planted in shelterbelts because of their
drought tolerance. A deep tap root system penetrates to lowered water
tables during the dry periods.

## Status

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status, such as state noxious status
and wetland indicator
values.![](media/image2.jpeg){width="2.6972222222222224in"
height="1.8111111111111111in"}

## Description 

*General*: Beech Family (Fagaceae). Native trees growning to 25 m tall,
with a broad, rounded crown, sometimes shrubby; branches and branchlets
with corky-winged projections; bark light gray, thick, rough, furrowed
into scaly plates and vertical flattened ridges. Leaves deciduous,
alternate, obovate, shaped like a fiddle, tapering to a wedge-shaped
base, 10--25 cm long and 6--12 cm wide, widest above the middle, with
2--3 rounded lobes on upper half of leaf and 5--7 deeper lobes on lower
half of leaf, dark green above, gray-green below, turning yellow or
brown in fall. Male and female flowers are borne in separate catkins on
the same tree (the species monoecious) on the current year\'s
branchlets. Acorns maturing in the first year, 2.5--5 cm long and wide,
with a deep, thick, fringed cup covering 1/2 to 3/4 of the acorn, the
scales knobby, long-pointed with narrow free tips. The common name (bur)
is in reference to the cap-covered acorn.

*Variation within the species:* Three varieties are commonly recognized
within the species.

Var. *depressa* (Nutt.) Engelm. (*Q. mandanensis* Rydb.) -- mostly along
the western margin of the Great Plains; small trees or shrubs with
smaller and less fringed cups and corky twigs.

Var. *macrocarpa* -- over most of the species range; trees with large
thick cups.

Var. *oliviformis* (Michx. f.) A. Gray) -- Iowa, Minnesota, South
Dakota, and North Dakota; trees with thinner and smaller cups. This is
sometimes considered within the typical variety.

Bur oak is a member of the white oak subgroup (subgenus *Lepidobalanus*)
and hybridizes with various related species, including northern pin oak
(*Q. ellipsoidalis*), white oak (*Q. alba*), swamp white oak (*Q.
bicolor*), overcup oak (*Q. lyrata*), swamp chestnut oak (*Q.
michauxii*), chinkapin oak (*Q. muehlenbergii*), post oak (*Q.
stellata*), live oak (*Q. virginiana*), and Gambel's oak (*Q.
gambelii*).

## Distribution

Bur oak is grows natively throughout much of the north-central United
States and the eastern Great Plains. It occurs from southern New
Brunswick and New England westward to the Dakotas and southeastern
Montana, and south to Tennessee, Arkansas, and the central prairies of
Texas -- with rare outliers in Louisiana, Mississippi, and Alabama. For
current distribution, please consult the Plant Profile page for this
species on the PLANTS Web site.

## Adaptation 

Bur oak grows in a range of habitats and moisture regimes -- from
prairies to valley floors and upland woods. It is a pioneer or early
seral species at prairie margins, but bur oak savannas have declined due
to grazing and fire suppression. It grows quickly on moist, rich
bottomlands but is relatively intolerant of flooding during the growing
season. At the north and west ends of its range, where bur oak occurs on
rocky bluffs with thin soil and where repeated fire also may be common,
it commonly grows as small trees or thickets of low shrubs. Young plants
grow well in full sun to partial sun.

Flowering occurs from April through June, just after leaves develop,
while fruiting occurs from August to November.

## Establishment

Minimum seed-bearing age is 35, with optimum seed production occurring
between 75--150 years, and trees are known to produce seed up to 400
years. Abundant acorns are produced every 2--3 years, with light crops
in the intervals. Most natural seed germination occurs during the fall
(directly after maturation) and unless germination is rapid, few seeds
survive predation by insects, small birds, and mammals. Litter-covered
acorns appear to be more vulnerable to rodents, insects, and fungus.

The taproot of young bur oaks rapidly penetrates into the soil,
sometimes growing more than one meter deep in the first growing season.
This early root development, along with high water-use efficiency, may
explain why bur oak can pioneer on droughty sites and can successfully
establish itself in competition with prairie shrubs and grasses. The
trees are slow-growing but long-lived and may reach ages approaching
1000 years.

## Management

Bur oak may be transplanted or it is easily propagated from seed. Seed
should be stored over winter in a cool, moist place at 1--4 C.
Germination frequency may be enhanced by stratifying 30--60 days at 1--5
C. but stratification is not required for germination, except for var.
*oliviformis*, which typically germinates during the spring. Most
natural seed germination occurs during the fall (directly after
maturation) but seed may be planted in either the spring or fall. Seeds
should be planted 1.2--2.5 centimeters deep, in groups of 2--3, spaced
at roughly 2 meter intervals.

Although strong and rapid development of the taproot contribute to
difficulty in transplanting, bur oak saplings can be obtained in
ball-and-burlap and they may be transplanted as young plants from
containers. Transplants are best made in spring.

Bur oak bark is thick and fire-resistant and larger trees often survive
fire. Grass fires often kill only seedlings and young trees, but even
seedlings may survive unless fires occur at short intervals or with
enough intensity of heat. Top-killed smaller trees (or those
mechanically damaged) sprout vigorously from the stump or root crown
after fire. In areas of frequent fire and strong herbivore browsing, the
underground portions may be much older and more extensive than the
continually resprouting aerial portions. Where fire suppression is
prevalent, bur oak communities may be replaced by more shade-tolerant
maple-basswood forests.

Few insects or diseases cause serious damage to bur oak. Oak lacebug
(*Corythucha arcuata*) may heavily defoliate bur oaks in shelterbelt
plantings, especially during dry weather. Oak wilt (*Ceratocystis
fagacearum*) is a less serious problem in bur oak than in species of red
oak, but the disease sometimes spreads through root grafts of adjacent
trees, and entire groves have been killed by the gradual expansion of
the disease from one center of infection.

## Cultivars, Improved and Selected Materials (and area of origin)

Contact your local Natural Resources Conservation Service (formerly Soil
Conservation Service) office for more information. Look in the phone
book under "United States Government." The Natural Resources
Conservation Service will be listed under the subheading "Department of
Agriculture."

## References

Johnson, P.S. 1990. *Quercus macrocarpa* Michx. Bur Oak. Pp. 686-692,
IN: R.M. Burns and B.H. Honkala. *Silvics of North America. Volume 2.
Hardwoods*. USDA, Forest Service Agric. Handbook 654, Washington, D.C.
SEP00.
\<http://willow.ncfes.umn.edu/silvics_manual/Volume_2/quercus/macrocarpa.htm\>

Nixon, K.C. and others 1993. *Quercus*. Pp. 445-506, IN: *Flora of North
America, North of Mexico. Vol. 3*. Oxford Univ. Press, New York, New
York. SEP00.
\<http://hua.huh.harvard.edu/cgi-bin/Flora/flora.pl?FLORA_ID=12395\>

Samuel Roberts Nobel Foundation 1999. *Noble foundation plant image
gallery*. Ardmore, Oklahoma. 29nov2000.
\<http://www.noble.org/imagegallery/index.html\>

Tirmenstein, D. 1988. *Quercus macrocarpa*. IN: W.C. Fischer (compiler).
*The fire effects information system* \[Database\]. USDA Forest Service,
Intermountain Research Station, Intermountain Fire Sciences Laboratory.
Missoula, Montana. SEP00.
\<http://www.fs.fed.us/database/feis/plants/tree/quemac/\>

## Prepared By

*Guy Nesom*

Formerly BONAP, North Carolina Botanical Garden, University of North
Carolina, Chapel Hill, North Carolina

## Species Coordinator

## *M. Kat Anderson*

USDA, NRCS, National Plant Data Center, c/o Plant Sciences Dept., Davis,
California

Edited: 19jun02 jsp; 29may03 ahv; 060809 jsp

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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*To file a complaint of discrimination write USDA, Director, Office of
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*Read about [Civil Rights at the Natural Resources Convervation
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