Northern Prairie Wildlife Research Center
Bur Oak (Quercus macrocarpa)
- Family: Beech (Fagaceae)
- Flowering: April-May.
- Field Marks: This oak is distinguished by its large acorn with a fringed cup and by its deep pair of sinuses just below the middle of the leaf.
- Habitat: Bottomland woods, along rivers and streams; many times in drier habitats.
- Habit: Tree up to 120 feet tall, with a rounded crown and stout branches.
- Bark: Dark brown or yellow-brown, rather deeply furrowed.
- Leaves: Alternate, simple, broader at the upper end, coarsely round-toothed, usually with a pair of deep sinuses just below the middle of the leaf, often with 5 or 7 lobes, not bristle-tipped, usually hairy on the lower surface, up to 14 inches long, up to 7 inches wide.
- Flowers: Male and female borne separately, but on the same tree, the male flowers in slender, drooping spikes; the female few in a group.
- Sepals: 0.
- Petals: 0.
- Stamens: 3-12.
- Pistils: Ovary inferior.
- Fruits: Acorns usually solitary, the nut ovoid to ellipsoid, dark brown, up to 1 3/4 inches long, the cup covering half to nearly all of the nut, hairy, the lowermost scales long-fringed.
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