How to identify Bur oak (Quercus macrocarpa)

How to identify Bur oak (Quercus macrocarpa)

Bur oak, also known as Prairie oak, Mossycup white oak

Bur oak boasts a sturdy frame with broad, deeply lobed leaves and an expansive, rugged bark. Its notable feature includes large acorns, encased in a fringed, cup-like structure reminiscent of burlap, which are among the biggest of any North American oak. The acorn caps, with their distinctively mossy fringe, are a key identifying characteristic. This species has robust branches that can withstand harsh conditions and develops a deep taproot, reflecting its adaptability to various soil types, whether they are rocky, clay-rich, or fertile. Its foliage turns a vibrant hue in autumn, coupled with considerable drought resistance and cold hardiness.

Lifespan: Perennial

Plant Type: Tree

Leaf Type: Deciduous

Quickly Identify Bur oak

Large acorns with fringed, burlap-like caps, notably mossy.

Distinctive deeply fringed cup encasing oval acorns, resembling chestnut bur.

Leaves with 5-7 deep, rounded lobes and greyish-green undersides.

Stems turn bold-textured, slightly corky, with multiple terminal buds.

Robust trunk with gray, furrowed bark developing pronounced vertical ridges.

Detailed Traits of Bur oak

Leaf Features

The leaves of bur oak are leathery and range from 6 to 12 inches (15 to 30 cm) long. They are dark green on the upper surface and greyish-green with fine dense pubescence below. The leaf margins feature 5 to 7 deep, rounded lobes, with the two middle sinuses nearly reaching the midrib, almost dividing the leaf in half. The base of the leaf is wedge-shaped.

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Flower Features

The flowers of bur oak bloom in spring as the leaves emerge. Male flowers form in drooping, elongated clusters or catkins, typically measuring around 2-4 inches (5-10 cm) long. These catkins are yellowish-green and inconspicuous. Female flowers are also in catkins but are shorter, usually less than 1 inch (2.5 cm). They are pale green and form at the twig tips. The flowers lack petals and have no noticeable scent, relying on the wind for pollination.

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Stem Features

Bur oak has stout stems that are yellow-brown to brown-gray. They become bold-textured and slightly corky after the first year. The stems feature multiple terminal buds, which are small, round, and may be somewhat pubescent, often surrounded by thread-like stipules. Lateral buds mirror these characteristics but are smaller. The distinct corky texture and coloration help distinguish the stems of bur oak, making them a notable feature for identification.

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Fruit Features

The fruit of bur oak is notable for its sizable, oval acorns, which can reach up to 1 1/2 inches (3.8 cm) in breadth. Each acorn is partially enveloped by a distinctive, deeply fringed cup that encases about 1/4 to 1/2 of its length, giving it a unique appearance reminiscent of a chestnut's spiny bur. The fruit's texture and shape, along with its singular cup design are key identification features. These acorns take a full year to mature, transforming to fulfill their role in the plant's reproductive cycle.

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Bur oak and Their Similar Plants

Northern red oak vs. Bur oak: What's The Difference?

Arguably the most popular hardwood in the US, lumber from northern red oak (Quercus rubra) is used for cabinets, flooring, veneers, trim, and more. When growing, the tree reaches a height of 15 to 23 m. The foliage on this tree is stunning, with dark green leaves in summer giving way to brilliant red in the fall.

English oak vs. Bur oak: What's The Difference?

The english oak (*Quercus robur*) is a deciduous tree native to Europe. It is a very long-lived tree; the oldest known specimens have been living for more than a thousand years. It is commonly represented in European mythologies as a symbol of strength, longevity, nobility, morale, and knowledge.

Pin oak vs. Bur oak: What's The Difference?

Quercus palustris, colloquially known as pin oak, is a deciduous tree native to North America. Due to its favorable growing qualities and beautiful bronze coloration in autumn, pin oak is one of the most common oak species used in landscaping.

Live oak vs. Bur oak: What's The Difference?

Quercus virginiana, commonly known as live oak, is a large evergreen tree native to coastal areas of southeast North America, known for its imposing, wide crown. Live oak is commonly cultivated as an ornamental in the American South, most often planted in avenues.

White oak vs. Bur oak: What's The Difference?

Quercus alba is a long-lived white oak with a broad canopy. The common name, white oak, refers to the color of its processed wood, which has a wide variety of uses - construction, for wine and whiskey barrels, making musical instruments and weapons in Japanese martial arts, etc. White oak is rarely cultivated as an ornamental due to its large size.

Water oak vs. Bur oak: What's The Difference?

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Willow oak vs. Bur oak: What's The Difference?

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Black oak vs. Bur oak: What's The Difference?

Black oak (Quercus velutina) is a deciduous tree with a rounded, wide crown, found on hills, slopes, and ridges of eastern North America. The common name refers to the color of its bark. Black oak often hybridizes with other plants of the genus Quercus.

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Key Facts About Bur oak

Attributes of Bur oak

Lifespan

Perennial

Plant Type

Tree

Plant Height

30 m

Spread

18 m to 24 m

Leaf Color

Green

Yellow

Brown

Stem Color

Brown

Green

Silver

Leaf type

Deciduous

The Toxicity of Bur oak

Slightly Toxic to Humans

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Scientific Classification of Bur oak

Phylum

Vascular plants

Class

Dicotyledons

Order

Beeches, walnuts, and allied trees

Family

Beech

Genus

Oaks

Species

Bur oak (Quercus macrocarpa)

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Distribution Map of Bur oak

Bur oak is native to most of North America. The plant prefers limestone soil, but it thrives in several habitats, including woodland, fertile slopes, damp bottomlands, and dry hillsides.

Native

Cultivated

Invasive

Potentially invasive

Exotic

No species reported

Learn More About the Bur oak

A Comprehensive Guide to Bur oak How to Grow and Care for Bur oak