Quercus macrocarpa | |
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A 400-year old tree in Missouri known as The Big Tree | |
Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Fagales |
Family: | Fagaceae |
Genus: | Quercus |
Subgenus: | Quercus subg. Quercus |
Section: | Quercus sect. Quercus |
Species: | Q. macrocarpa |
Binomial name | |
Quercus macrocarpa | |
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Generalized natural range | |
Synonyms [2] | |
List
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Quercus macrocarpa, the bur oak or burr oak, is a species of oak tree native to eastern North America. It is in the white oak 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 μακρός makrós "large" and καρπός karpós "fruit"), and are important food for wildlife.
Quercus macrocarpa is a large deciduous tree growing up to 30 metres (98 feet), rarely 50 m (160 ft), in height, [3] and is one of the most massive oaks with a trunk diameter of up to 3 m (10 ft). It is one of the slowest-growing oaks, with a growth rate of 30 centimetres (12 in) per year when young. However, one source states that a well-established tree can grow up to 51 cm (20 in) per year. [4] [ unreliable source? ] A 20-year-old tree will be about 18 m (60 ft) tall if grown in full sun.[ citation needed ] 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. [5] The bark is gray with distinct vertical ridges. [3]
The leaves are 7–15 cm (2+3⁄4–6 in) long and 5–13 cm (2–5 in) 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. [4] The flowers are greenish-yellow catkins, produced in the spring. The acorns are very large, 2.5–5 cm (1–2 in) long and 2–4 cm (3⁄4–1+1⁄2 in) 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. [3]
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 (swamp white oak), [6] Quercus lyrata (overcup oak), and Quercus alba (white oak). It hybridises with several other species of oaks.
Two varieties are accepted in Kew's Plants of the World Online: [7]
Quercus macrocarpa is widespread in the Atlantic coastal plain from New Brunswick to North Carolina, west as far as Alberta, eastern Montana, Wyoming, and northeastern New Mexico. The vast majority of the populations are found in the eastern Great Plains, the Mississippi – Missouri – Ohio Valley, and the Great Lakes region. [8]
Bur oaks primarily grow in a temperate climate on the western oak–hickory forested regions in the United States and into Canada. [9] It commonly grows in the open, away from dense forest canopy. For this reason, it is an important tree on the eastern prairies, often found near waterways in otherwise more forested areas, where there is a break in the canopy. It is drought resistant, possibly because of its long taproot. At the end of the growing season, a one-year sapling may have a taproot 1.37 m (4+1⁄2 ft) deep and a lateral root spread of 76 cm (2+1⁄2 ft). [10] The West Virginia state champion bur oak has a trunk diameter of almost 3 m (10 ft).
Large bur oaks, older than 12 years, [11] are fire-tolerant because of their thick bark. [10] One of the bur oak's most common habitats, especially in Midwestern United States, is the oak savanna, 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. [11]
The acorns are the largest of any North American oak [10] 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 evolutionary 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.
Many species of arthropods form galls on the leaves and twigs, including Aceria querci (a mite) and numerous cynipid wasps: Acraspis macrocarpae , Acraspis villosa , Andricus chinquapin , Andricus dimorphus , Andricus foliaformis , Andricus flavohirtus , Andricus quercuspetiolicola , Callirhytis flavipes , Disholcaspis quercusmamma , Neuroterus floccosus , Neuroterus saltarius , Neuroterus umbilicatus , Philonix nigra , and Phylloteras poculum . [12]
Bur oak blight is caused by a fungal pathogen Tubakia iowensis . [13] 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). [13]
Quercus macrocarpa is cultivated by plant nurseries for use in gardens, in parks, and on urban sidewalks. Among the white oaks, it is one of the most tolerant of urban conditions, and is one of the fastest-growing of the group.[ citation needed ] It has been planted in many climates, ranging northwards to Anchorage, Alaska, and as far south as Mission, Texas.[ citation needed ] It withstands chinook conditions in Calgary, Alberta.[ citation needed ] It is drought tolerant. [6]
The wood of Quercus macrocarpa is commercially valuable; it is durable, used for flooring, fence posts, cabinets, and barrels. [10] [15] The acorns can be eaten boiled and raw. [16] Native Americans have used the astringent bark to treat wounds, sores, rashes, and diarrhea. [15] [16]
Many places are named after the burr oak, such as Burr Oak State Park in Ohio, the cities of Burr Oak, Iowa and Burr Oak, Kansas, and the village of Burr Oak, Michigan. Burr Oaks (1947) is a volume of poetry by Richard Eberhart. [17]
Quercus kelloggii, the California black oak or Kellogg oak, is an oak in the red oak section native to western North America. Although genetically separated from them for more than 20 million years, its leaves are remarkably similar in appearance to several other members of the red oak section including the red oak and the black oak found in eastern and central North America.
Quercus rubra, the northern red oak, is an oak tree in the red oak group. It is a native of North America, in the eastern and central United States and southeast and south-central Canada. It has been introduced to small areas in Western Europe, where it can frequently be seen cultivated in gardens and parks. It prefers good soil that is slightly acidic. Often simply called red oak, northern red oak is so named to distinguish it from southern red oak (Q. falcata), also known as the Spanish oak. Northern red oak is sometimes called champion oak.
Quercus montana, 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 southern Michigan. It is also sometimes called rock oak because of its presence in montane and other rocky habitats.
Quercus alba, the white oak, is one of the preeminent hardwoods of eastern and central North America. It is a long-lived oak, native to eastern and central North America and found from Minnesota, Ontario, Quebec, and southern Maine south as far as northern Florida and eastern Texas. Specimens have been documented to be over 450 years old.
Quercus palustris, also called pin oak, swamp oak, or Spanish oak, is a tree in the red oak section of the genus Quercus. Pin oak is one of the most commonly used landscaping oaks in its native range due to its ease of transplant, relatively fast growth, and pollution tolerance.
Quercus muehlenbergii, the chinquapinoak, is a deciduous species of tree in the white oak group. The species was often called Quercus acuminata in older literature. Quercus muehlenbergii is native to eastern and central North America. It ranges from Vermont to Minnesota, south to the Florida panhandle, and west to New Mexico in the United States. In Canada it is only found in southern Ontario, and in Mexico it ranges from Coahuila south to Hidalgo.
Quercus velutina, the black oak, is a species of oak in the red oak group, native and widespread in eastern and central North America. It is sometimes called the eastern black oak.
Quercus robur, the pedunculate oak or English oak, is a species of flowering plant in the beech and oak family, Fagaceae. It is a large tree, native to most of Europe and western Asia, and is widely cultivated in other temperate regions. It grows on soils of near neutral acidity in the lowlands and is notable for its value to natural ecosystems, supporting a very wide diversity of herbivorous insects and other pests, predators and pathogens.
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 hybrids with bur oak where they occur together in the wild.
Quercus garryana is an oak tree species of the Pacific Northwest, with a range stretching from southern California to southwestern British Columbia. It is commonly known as the Garry Oak, Oregon white oak or Oregon oak. It grows from sea level to an altitude of 690 feet in the northern part of its range, and from 980 to 5,900 ft in the south of the range in California. The eponymous Nicholas Garry was deputy governor of the Hudson's Bay Company.
Quercus cerris, the Turkey oak or Austrian oak, is an oak native to south-eastern Europe and Asia Minor. It is the type species of Quercus sect. Cerris, a section of the genus characterised by shoot buds surrounded by soft bristles, bristle-tipped leaf lobes, and acorns that usually mature in 18 months.
Quercus douglasii, known as blue oak, is a species of oak endemic to California, common in the Coast Ranges and the foothills of the Sierra Nevada. It is California's most drought-tolerant deciduous oak, and is a dominant species in the blue oak woodland ecosystem. It is occasionally known as mountain oak and iron oak.
Quercus gambelii, with the common name Gambel oak, is a deciduous small tree or large shrub that is widespread in the foothills and lower mountains of western North America. It is also regionally called scrub oak, oak brush, and white oak.
Quercus coccinea, the scarlet oak, is a deciduous tree in the red oak section Lobatae of the genus Quercus, in the family Fagaceae.
Quercus acutissima, the sawtooth oak, is an Asian species of oak native to China, Tibet, Korea, Japan, Indochina and the Himalayas. It is widely planted in many lands and has become naturalized in parts of North America.
Quercus lobata, commonly called the valley oak or roble, is the largest of the California oaks. It is endemic to the state, growing in interior valleys and foothills from Siskiyou to San Diego counties. Deciduous, it requires year-round groundwater, and may live up to 600 years. Its thick, ridged bark and deeply lobed leaves are characteristic, and assist in identification.
Quercus lyrata, the overcup oak, is an oak in the white oak group. 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 eastern and south-central United States, in all the coastal states from New Jersey to Texas, inland as far as Oklahoma, Missouri, and Illinois. There are historical reports of it growing in Iowa, but the species appears to have been extirpated there. It is a slow-growing tree that often takes 25 to 30 years to mature. It has an estimated lifespan of 400 years.
Quercus nigra, the water oak, is an oak in the red oak group, native to the eastern and south-central United States, found in all the coastal states from New Jersey to Texas, and inland as far as Oklahoma, Kentucky, and southern Missouri. It occurs in lowlands and up to 450 meters in elevation.
Quercus arizonica, the Arizona white oak, is a North American tree species in the beech family. It is found in Arizona, New Mexico, western Texas, Sonora, Chihuahua, Coahuila, Sinaloa, and Durango.
Quercus hartwissiana, the Strandzha oak, is a species of oak, native to southeastern Bulgaria, northern Asia Minor along the Black Sea, and the Caucasus. It was described by the Finnish-born Russian botanist and entomologist Christian von Steven in 1857.
Burr Oaks, Oxford University Press (New York, NY), 1947.