Bur Oak
Quercus macrocarpa · Deciduous Broadleaf Hardwood
Plant Family
Fagaceae
Tree Category
Shade Tree / Forest Tree / Wildlife Tree
Variety / Cultivar
Native species (Common variety)
Hardiness Zones
USDA Zones 3-8. Extremely cold-hardy and heat-tolerant.
About This Tree
A massive, long-lived tree with a broad, spreading crown and stout branches. It is known for its rugged appearance, thick corky bark, and largest acorns of all North American oaks. Growth rate is slow to moderate, forming a majestic rounded silhouette at maturity.
Leaf Characteristics
Simple, alternate, 6-12 inches long. Obovate shape with deep central sinuses that nearly cut the leaf in half. Dark green leathery tops with silvery-green fuzzy undersides. Turn yellow-brown in fall.
Bark Characteristics
Grayish-brown, very thick and deeply furrowed into vertical ridges. Younger branches often develop prominent corky wings or ridges which are a primary identification feature.
Growing Information
Origin Region
Native to North America, primarily the Midwestern United States and Central Canada.
Growing Season
Leafs out in late spring (May); flowers from April to May; acorns ripen in autumn (September-October); enters dormancy in late fall.
Sunlight & Water Needs
Full sun preferred; highly drought-tolerant once established. Prefers well-drained loamy soils but is remarkably adaptable to various soil types including heavy clay.
Mature Size
70-80 feet tall with a similar spread of 70-80 feet. Can reach over 100 feet in ideal conditions. Lifespan can exceed 200-300 years.
Special Characteristics
Exceptional fire resistance due to thick bark. High tolerance for urban pollution and alkaline soils. Acorn caps are distinctively 'fringed' with burlike hair-like scales, giving the tree its name.
Wildlife & Ecology
Critical ecological value; acorns are a primary food source for deer, turkeys, squirrels, and wood ducks. Support hundreds of species of lepidoptera (butterflies and moths) as a host plant.