Bur Oak (also known as Mossycup Oak)
Kingdom: Plantae, Division: Tracheophyta, Class: Magnoliopsida, Order: Fagales, Family: Fagaceae, Genus: Quercus, Species: Quercus macrocarpa · Fagaceae (Beech or Oak family) · Simple, Deciduous
Species
Quercus macrocarpa
Leaf Type
Simple, Deciduous
Family
Fagaceae (Beech or Oak family)
Shape
Obovate with deep, rounded lobes. Features a classic 'fiddle' or 'hourglass' shape, defined by deep sinuses near the middle and a wide, cap-like upper terminal lobe with smaller shallow teeth or lobes.
Size
Approximately 6 to 10 inches long and 3 to 5 inches wide, which matches the typical mature size range for this species (5 to 12 inches long).
Margin
Lobed with rounded, broad tips (lacks bristle tips typical of red oaks). Sinuses near the middle extend deep toward the midrib.
Arrangement
Alternate, concentrated near the ends of stout twigs.
Rarity
Very Common within its native range across North America.
Color & Pattern
Deep green to dark forest green on the upper surface with a lighter, slightly paler yellowish-green undersurface. The prominent midrib and primary veins are pale yellowish-green.
Venation Pattern
Pinnate, with strong secondary veins radiating from the main midrib directly into each major lobe.
Texture & Surface
Leathery (coriaceous) and slightly glossy to dull on the upper surface (adaxial); fine, soft, whitish puberulent hairs are typically present on the underside (abaxial).
Description
The Bur Oak is a majestic, long-lived deciduous tree growing up to 70–100 feet tall with a wide, spreading crown and thick, deeply ridged, fire-resistant bark. The leaves exhibit a characteristic fiddle shape with deep central indents. In autumn, leaves turn yellow-green to brownish-copper. It produces massive acorns with distinctive fringe-like, mossy cups.
Key Features
Deeply lobed leaf with a narrow waist (fiddle shape) near the lower half and a large, broad terminal lobe. Absence of sharp bristle tips on the leaf lobes (distinguishing white oak group from red oak group). Acorns surrounded by a fringed 'mossy' cap.
Habitat
Thrives in dry upland prairies, oak savannas, rich bottomlands, along streams, and open woodlands. Extremely drought-resistant and fire-tolerant due to thick bark.
Geographic Range
Native to central and eastern North America, spanning from Saskatchewan and Quebec south to Texas and Virginia.
Condition Notes
Good condition overall. Showcases minor insect herbivory along the lower margins and a small hole, along with minor necrotic insect spots, which is standard for healthy wild oak foliage in mid-to-late summer.
Interesting Facts
Bur Oaks are famous for their fire resistance, allowing them to form historical oak savannas across North American prairies. They can live for over 300 to 400 years and bear the largest acorns of any native North American oak.
Medicinal & Uses
Wood is high-quality white oak lumber used for flooring, cabinetry, barrels (cooperage), and fence posts. Native Americans used tannin-rich bark extracts for astringent, anti-inflammatory washes for wounds and insect bites.
Ecological Role
A keystone species in prairie savannas. Provides essential food for squirrels, deer, wild turkeys, and blue jays. Hosts hundreds of native caterpillar species including giant silkmoths.
Similar Species
White Oak (Quercus alba) has more evenly lobed leaves without the deep central waist. Swamp White Oak (Quercus bicolor) has shallower lobes and lacks the distinct cap-like top lobe.
Foraging Tips
Look for large trees in open parks or edge habitats. The acorns are edible after multiple hot or cold water leachings to extract bitter tannins, producing a mild flour or meal.
Toxicity Warning
Mildly Toxic if raw acorn meat or leaves are ingested in large quantities by livestock or domestic pets due to high tannin content. Acorns are safe for humans only after proper processing/leaching.