Quercus macrocarpa
A large, slow-growing oak with the largest acorns of any North American oak.
Quercus macrocarpa, commonly known as the bur oak or burr oak, is a species of oak tree native to central and eastern North America. It belongs to the white oak section and is also called mossycup oak, mossycup white oak, or scrub oak. The acorns are the largest of any North American oak, making the tree an important food source for wildlife.
- height
- up to 30 m (98 ft), rarely 50 m (160 ft)
- trunk_diameter
- up to 3 m (10 ft)
- lifespan
- 200 to 300 years, may live up to 400 years
- growth_rate
- 30 cm (12 in) per year when young; one source states up to 51 cm (20 in) per year for well-established trees
- acorn_size
- 2.5–5 cm (1–2 in) long, 2–4 cm (3⁄4–1+1⁄2 in) broad
- range
- Atlantic coastal plain from New Brunswick to North Carolina, west to Alberta, Montana, Wyoming, and northeastern New Mexico
Lore & Background
Quercus macrocarpa is a large deciduous tree that can reach up to 30 metres (98 feet) in height, rarely 50 m (160 ft), 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, though a well-established tree can grow up to 51 cm (20 in) per year according to one source. A 20-year-old tree in full sun will be about 18 m (60 ft) tall. The bark is gray with distinct vertical ridges, and the leaves are 7–15 cm long, variable in shape, with a lobed margin. The acorns are very large, with a large cup that wraps much of the way around the nut, featuring large overlapping scales and often a fringe at the edge.
Reader's Guide
The bur oak is significant for its ecological and commercial roles. Its acorns, the largest of any North American oak, are an important wildlife food, consumed by animals such as American black bears, deer, and porcupine. The tree is drought resistant, likely due to its long taproot, and is fire-tolerant after 12 years because of its thick bark. It commonly grows in oak savannas, where fires historically occurred, and without fire it is often succeeded by more shade-tolerant species. The wood is commercially valuable, used for flooring, fence posts, cabinets, and barrels. Native Americans have used the astringent bark to treat wounds, sores, rashes, and diarrhea. The bur oak is also cultivated in gardens and urban settings, and its range extends farther north than any other North American oak. Many places are named after the burr oak, including Burr Oak State Park in Ohio and several towns.
Did You Know?
- The acorns of Quercus macrocarpa are the largest of any North American oak.
- The species name macrocarpa comes from Ancient Greek for 'large fruit'.
- Bur oaks commonly live 200 to 300 years and may live up to 400 years.
- The bur oak is the only known host plant of Bucculatrix recognita caterpillars.
More in Flowering Trees & Shrubs 1-20
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