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Bur Oak

Quercus macrocarpa

Summary 3

Quercus macrocarpa, the bur oak, 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 central United States and eastern and central Canada. This plant is also called mossycup oak and mossycup white oak.

Description 4

Family:
Fagaceae (Beech)

Height:
80 to 120 feet at maturity

Habit and Lifespan:
Single-stemmed tree; Crown is broadly spreading to oval in shape; DBH up to 5’, typically closer to 3-4’; Branches are gnarled and crooked; Slow-growing and long-lived (up to 400 years); Often a dominant canopy tree

Leaves:
Leaves (up to 8” long and 6” wide) are alternately attached and have a typical oak shape - obovate (reaching their broadest around ⅔ of the way up the length of the leaf) and multi-lobed. Leaves have 5-7 pairs of main lobes with rounded tips which may be further divided by shallow sinuses. Main sinuses are deeper near the stem, typically becoming shallower as they move towards the leaf tip, which has a fan-like appearance.

Bark:
Young bark is brown to gray-brown and corky, with flat ridges. Mature bark is thick, corky, and gray to gray-brown, retaining its flat ridges while developing deep, irregular furrows. Bark may slough off the main trunk of mature trees in large patches, revealing smooth gray bark.

Flower:
Male flowers grow in groups of yellow-green to yellow, dangling, string-like clusters (up to 5” long) called catkins. Female flowers (up to ⅛” across) are green and inconspicuous, emerging from stout stalks at the newest leaf axils.

Fruit:
Fruit (½-1” long) is a reddish-brown, round to egg-shaped nut (acorn) with a rough, scaly, brown cap that covers half or more of the nut. The lower edge of the cap is fringed with thick green hairs that turn brown with age.

Bloom time:
April-May

Fall color:
Golden-yellow to copper-brown

Nicknames:
None

Habitat:
Bur Oak prefers full to partial sun and well-drained, loamy soils, but will tolerate soil conditions ranging from dry to moist, and can thrive in sand, clay, and high pH soils. It is commonly found growing in woodlands, savannas, and prairies, and is a commonly planted landscape tree.

Wildlife Benefits:
Acorns are a food source for many species of songbirds and gamebirds, including the Greater Prairie Chicken (Tympanuchus cupido, a Minnesota special concern species), as well as a variety of mammals, ranging from bears to mice. Foliage is a food source for many species of caterpillars, long-horned beetles, treehoppers, and other insects, including the Northern Walkingstick (Diapheromera femorata), in turn providing an important food source for insectivorous birds. Provides nesting habitat for squirrels and many species of birds, including owls.

Notes:
This species is tolerant of fire, drought, and extreme cold, but intolerant of flooding.
It is a popular species for woodworking.

References:
https://www.minnesotawildflowers.info/tree/bur-oak
https://www.illinoiswildflowers.info/trees/plants/bur_oak.htm
https://plants.ces.ncsu.edu/plants/quercus-macrocarpa/
https://www.fs.fed.us/database/feis/plants/tree/quemac/all.html

Range 4


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Sources and Credits

  1. (c) Ramsey-Washington Metro Watershed District, all rights reserved, uploaded by Ramsey-Washington Metro Watershed District
  2. (c) natcapfor, some rights reserved (CC BY-NC)
  3. Adapted by Ramsey-Washington Metro Watershed District from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Quercus_macrocarpa
  4. (c) Ramsey-Washington Metro Watershed District, some rights reserved (CC BY-SA)

More Info

iNaturalistAU Map

Family Fagaceae
Habit Tree
Life cycle perennial
Origin native
Bloom time (4) April, (5) May
*sites Lake Phalen, Snail Lake
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