Quercus macrocarpa

Bur Oak

Bur Oak, Little Beartrack Lake, BWCAW
Photo © by Earl J.S. Rook

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The natural history of the northwoods


Name:

  • Quercus, the Latin for Oak
  • macrocarpa, from the Greek, makros (makros), "long" , and karpos (carpos), "fruit", hence "large fruited", a reference to the large acorns.
  • Common name from from the "bearded" acorn stem and cup
  • Other common names include Mossy-cup Oak, Chêne à gros fruits

Taxonomy:

  • Kingdom Plantae, the Plants
    • Division Magnoliophyta, the Angiosperms (flowering plants)
      • Class Magnoliopsida, the Dicotyledons
      • Subclass Hamamelidae
        • Order Fagales
          • Family Fagaceae, the Beeches
            • Genus Quercus, the Oaks
  • Taxonomic Serial Number: 19287

Description:

  • A large spreading deciduous tree to 120' or more in height.
  • Leaves alternate and simple, broader at the tip than the base, and are 4"-14" long and up to 7" wide. They have 5 to 9 coarsely rounded lobes, with the sinuses (incised areas between the lobes) below the middle of the leaf being deeply incised almost to the midrib of the leaf. The leaves are dark green on the upper surface, and typically smooth. The underside of the leaf is paler green and slightly hairy.
  • Stem
    • Trunk straight, sometimes flared at base, to 5' diameter or more.
    • Branches thick and spreading
    • Twigs grayish or reddish, 2-4 mm diam., often forming extensive flat, radiating, corky wings, finely pubescent.
    • Bark dark gray, scaly or flat-ridged. dark brown and deeply furrowed.
  • Roots deep taproot
  • Flowers Male and female flowers occur separately, but on the same tree at leaf out. The males are clusters of drooping catkins.
  • Fruit a large acorn, up to 2" long

Identification:

Distribution:

  • Extreme southeastern Saskatchewan and Manitoba to New Brunswick, south through the Great Plains to Texas and northeast through Louisiana, Arkansas, Tennessee, Kentucky, West Virginia, Pennsylvania, and New Jersey.

Habitat:

  • Bottomlands, riparian slopes, poorly drained areas, prairies, usually on limestone or calcareous clays (in nw part of range on dry slopes and ridges, prairies)
  • Quercus macrocarpa is one of our most cold-tolerant oak species; it also endures a wide variety of other harsh conditions including poor dry soils and wet, poorly drained, and inundated locations.
  • Bur oak thrives under a broad range of environmental conditions. It survives in dry, mineral-poor soils as well as wet soils. , and it tap root sallows it to survive drought. It is the most fire-resistant of the oaks and is consequently common in savannas and prairie groves. Bur oak is also one of the most cold-tolerant oaks.
  • The tree is slow growing, but long lived, and may reach ages approaching 1000 years. Bur oak reproduces by seed and stump sprouting. It is commonly browsed by herbivores and grows in areas where fire is more frequent (savannas, prairies). Young bur oak shoots may be browsed or burned back only to re-sprout numerous times. This results in a root system that is older than the aerial portion of the plant.

Fire:

  • Its thick bark protects it from fire

Associates:

History:

  • Native Americans used Quercus macrocarpa medicinally to treat heart troubles, cramps, diarrhea, Italian itch, and broken bones, to expel pinworms, and as an astringent

Uses:

  • Wood is durable and of high quality. It is used for cabinetry, barrels, hardwood flooring and fence posts.
  • Native Americans used bur oak to treat heart ailments, diarrhea, broken bones, and as an astringent (to close bleeding wounds).

Reproduction:

Propagation:

  • By seed

Cultivation:

  • Hardy to USDA Zone 3 (average minimum annual temperature -40ºF)
  • Cultural Requirements
    • Full sun
    • Well-drained soil, pH 4.6 - 8.0
  • Size 40'-80"W x 60'-120'H
  • Growth rate moderate

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Last updated on 4 March, 2006