Bur oak

Bur oak

name = Bur Oak
status = LR/lc | status_system = IUCN2.3

image_width = 240px
image_caption = Bur Oak leaves and acorn
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Fagales
familia = Fagaceae
genus = "Quercus"
sectio = "Quercus"
species = "Q. macrocarpa"
binomial = "Quercus macrocarpa"
binomial_authority = Michx.

The Bur Oak, ("Quercus macrocarpa"), sometimes spelled Burr Oak, is a species of oak in the white oak section "Quercus" sect. "Quercus", native to North America in the eastern and midwestern United States and south-central Canada. This plant is also called Mossycup oak and Mossycup white oak. It occurs from the Appalachian Mountains west to the middle of the Great Plains, extending to central Texas, across southernmost Manitoba, Ontario and Quebec, east to the Atlantic Coast in southern New Brunswick, and down the coast to Delaware. Bur Oak is the state tree of Iowa.

It is a large deciduous tree growing up to 30 m (100 ft), rarely 37 m (120 ft), in height, and is one the most massive oaks with a trunk diameter of up to 3 m (10 ft); reports of taller trees occur, but have not been verified. It is one of slowest-growing oaks, with growth rate of 30 cm (1 ft) per year when young. A 20-year-old tree will be about 6 m (20 ft) tall. It commonly lives to be 200 to 300 years old, and may become significantly older. The bark is a medium gray and somewhat rugged.

The leaves are 7-15 cm (3-6 in) long and 5-13 cm (2-5 in) broad, variable in shape, with a lobed margin. Most often, the basal 60% is narrower and deeply lobed, while the apical 40% is wider and has shallow lobes or large teeth. The flowers are greenish-yellow catkins, produced in the spring. The acorns are very large, 2-5 cm (0.8-2 in) long and 2-4 cm (0.8-1.5 in) broad, with 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.

Bur Oak is sometimes confused with Overcup oak and White oak.


Bur Oak typically grows in the open, away from forest canopy. For this reason, it is an important tree on the eastern prairies, where it is often found near waterways in more forested areas, where there is a break in the canopy. It is also a fire-resistant tree, and possesses significant drought resistance by virtue of a long taproot. New trees may, after two to three years of growth, possess a 1-2 m deep taproot. The West Virginia state champion Bur Oak has a trunk diameter of almost 3 m (9 feet).

The acorns are the largest of any North American oak, and are an important wildlife food; American Black Bears sometimes tear off branches to get them. However, heavy nut crops are borne only every few years. In this strategy, known as masting, 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 and porcupine, eat the leaves, twigs and bark. Cattle are heavy browsers in some areas. The bur oak is the only known foodplant of "Bucculatrix recognita" caterpillars.

Cultivation and uses

Bur oak makes an outstanding ornamental tree. It is one of the most tolerant of urban conditions of the white oaks, and is one of the fastest-growing of the group. It has been planted in many places north to Anchorage, Alaska and as far south as Edinburg, Texas. It withstands chinook conditions at Calgary, Alberta.

The wood is high quality, and is almost always marketed as "white oak".

The name sometimes is spelled "burr oak", as for example in Burr Oak State Park in Ohio, the city of Burr Oak, Kansas, the village of Burr Oak, Michigan, and in the title "Burr Oaks" by poet Richard Eberhart.

It is also less commonly called "burl oak," as in the Burl Oaks Country Club in Mound, Minnesota, and the Burl-Oak Theatre Company in Oakville, Ontario


* [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501058 Flora of North America: "Quercus macrocarpa"]
* [http://plants.usda.gov/java/profile?symbol=QUMA2 USDA Plants Profile: "Quercus macrocarpa"]
* [http://www.cas.vanderbilt.edu/bioimages/species/frame/quma2.htm "Quercus macrocarpa" images at bioimages.vanderbilt.edu]

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Look at other dictionaries:

  • Bur oak — Oak Oak ([=o]k), n. [OE. oke, ok, ak, AS. [=a]c; akin to D. eik, G. eiche, OHG. eih, Icel. eik, Sw. ek, Dan. eeg.] [1913 Webster] 1. (Bot.) Any tree or shrub of the genus {Quercus}. The oaks have alternate leaves, often variously lobed, and… …   The Collaborative International Dictionary of English

  • Bur oak — Bur Bur, Burr Burr (b[^u]r), n. [OE. burre burdock; cf. Dan. borre, OSw. borra, burdock, thistle; perh. akin to E. bristle (burr for burz ), or perh. to F. bourre hair, wool, stuff; also, according to Cotgrave, the downe, or hairie coat,… …   The Collaborative International Dictionary of English

  • bur oak — ☆ bur oak n. a North American white oak (Quercus macrocarpa) having large acorns with fringed cups; mossy cup oak …   English World dictionary

  • bur oak — noun medium to large deciduous oak of central and eastern North America with ovoid acorns deeply immersed in large fringed cups; yields tough close grained wood • Syn: ↑burr oak, ↑mossy cup oak, ↑mossycup oak, ↑Quercus macrocarpa • Hypernyms:… …   Useful english dictionary

  • bur oak — an oak tree, Quercus macrocarpa, of eastern North America, having shiny, dark green leaves, light gray deeply ridged bark, and very large acorns with a fringed cup, yielding a hard, durable wood: the state tree of Illinois. [1805 15, Amer.] * * * …   Universalium

  • bur oak — stambiavaisis ąžuolas statusas T sritis vardynas apibrėžtis Bukinių šeimos dekoratyvinis, medieninis augalas (Quercus macrocarpa), paplitęs Šiaurės Amerikoje. atitikmenys: lot. Quercus macrocarpa angl. bur oak; large acorn oak; mossy cup oak vok …   Lithuanian dictionary (lietuvių žodynas)

  • bur oak — noun Date: 1815 a usually large oak (Quercus macrocarpa) of eastern North America having oval acorns enclosed in a fringed cap and tough close grained wood …   New Collegiate Dictionary

  • bur oak — noun a North American oak with large fringed acorn cups and wood formerly used in shipbuilding. [Quercus macrocarpa.] …   English new terms dictionary

  • Bur Oak (VIVA) — Infobox YRT station= Bur Oak Avenue Vivastation type= Proposed Vivastation line= Viva Purple (proposed) Viva Green (proposed) nextstop= Wootten Way (westbound, proposed) Cornell (eastbound, proposed) connections= 1 Highway 7 (proposed) 2A 14th… …   Wikipedia

  • Oak savanna — Oak savanna, California An oak savanna is a type of savanna, or lightly forested grassland, where oaks (Quercus spp.) are the dominant tree species. These savannas were maintained historically through wildfires set by lightning, grazing, low… …   Wikipedia

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