Bur oak

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More names for this tree

Anishinaabemowin: Mitigomizh

Dakota: Utahuçaŋ (oak tree)

The Dakota and Anishinaabe were among the earliest people to name Minnesota’s plants and animals, as well as to understand them in relation to Minnesota’s climate and seasons. Those original names are still in use, and several are included on the Season Watch website. However, complete translations were not available.

Latin (or scientific name): Quercus macrocarpa

The scientific community has a convention of assigning agreed-upon Latin names to every kind of organism. Using scientific names helps people communicate confidently about the same organism and organize lifeforms based on how closely related they are.

Page contents

About the bur oak

Visual guide to phenology

Graphs and historical data

More resources

Grand bur oak in a grassland setting, gray-blue sky and green grass.
May 30, 2022, Olmsted County, Minnesota
Photo © rmdnat, some rights reserved (CC-BY-NC)
iNaturalist observation

About the bur oak

  • Common in Minnesota, the bur oak can be distinguished by its deeply lobed, shiny leaves.
  • Before European settlement, a type of ecosystem called oak savanna was common in Minnesota. Bur oaks are a key species in these now threatened habitats.
  • Bur oaks have both male and female flowers growing on the same tree. In Minnesota, the flowers typically emerge in April or May.
  • The fruit of an oak is called an acorn. Bur oaks' acorns are the largest of all Minnesota's native oak species.
  • A deciduous tree, bur oak leaves turn yellow or orange in fall. However, the brown leaves cling to the tree all winter instead of falling to the ground.
  • Fun fact: Bur oak acorns can be eaten after boiling to remove bitter-tasting tannins. The acorns are also a favorite food source for many forest animals.

Visual guide to phenology

Watch for the appearance of leaves, flowers, and fruits. Take notice of when flowers open and fruits ripen.

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Note to observers

This page explains general clues to watch for when observing bur oak phenology. However, this page does not instruct observers on how to identify this plant or collect data in a standardized way.

Bur oak with bare branches against a brilliant blue sky
Bare branch shows the gnarled, knobby texture of bur oak's bark.
Close-up image showing buds at the tip of an oak twig.
Close-up image showing buds on a twig and the empty, gray cap of last year's acorn.
Bright green buds at the tip of twigs where flowers and leaves will unfold
Tip of a twig with tiny soft green leaves increasing in size. Flowers clustered in cord-like structures have appeared.
Tip of oak branch with about 20 leaves increasing in size. Also, many cord-like flower structures hang from the branch.
Close-up of bur oak's male flowers. Bright lime-green clusters of tiny, bead-like shapes are arranged in tassels, called "catkins".
Female flowers are tiny and grow in the axil, where the leaf petiole attaches to the stem.
Zoomed in image of the tiny female flower on a bur oak.
Spent flowers have turned from green and supple to brown and crisp.
The first sign of acorns - tiny, green, scale-covered spheres.
Three bright green acorns form near the base of leaves. The acorn caps have a frilled edge and bumpy exterior.
As acorns (or fruits) ripen, they turn from green to brown.
Oak leaves with changing color, from green to yellow and brownish-orange.
Dry, brown leaves on the twig of an oak tree. Backdrop is a snowy scene.

Graphs and historical data

Note: The Orientation Center provides a map, as well as information on reading graphs; interpreting summary statistics, who collected the data and how; and how to download datasets for independent exploration.

Ramsey County

Leaf budbreak

  • Earliest: April 5 (occurred in 1987)
  • Average: April 24
  • Latest: May 31 (occurred in 2013)
Scatterplot showing bur oak phenology in Ramsey County, Minnesota

Download this dataset (.csv file)

More resources

Bur oak (Quercus macrocarpa) in the Minnesota Biodiversity Atlas

Bur oak (Quercus macrocarpa) in Nature's Notebook

 

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Times of year

Co-author: Audrey Negro, Minnesota Master Naturalist