Quercus ellipsoidalis (Northern Pin Oak)

Plant Info
Also known as:
Genus:Quercus
Family:Fagaceae (Beech)
Life cycle:perennial woody
Origin:native
Habitat:part shade, sun; heavier, well drained soil; forest
Bloom season:mid May
Plant height:over 100 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: indistinct

[photo of flowers] Male and female flowers are borne separately on the same branch, the males on 1½ to 4 inch long green, string-like clusters (called catkins) from bud clusters at the tip of the previous season's growth. 1 to 3 female flowers, with bright red styles and a short, stubby, green stalk, sit in the leaf axils of new growth.

Leaves and bark: Leaf attachment: alternate Leaf type: lobed

[photo of leaves] Leaves are simple and alternate, the blade oval or elliptic to nearly round in outline, 2¾ to 5½ inches long and almost as wide on a ¾ to 1¾ inch stalk. Each side has 2 to 4 primary, finger-like lobes, each with 2 to 5, sharply pointed secondary lobes at their tips. The sinuses between the lobes are more often broad and rounded, extending over half way or nearly to the central vein. Upper surface is deep green and glossy, the lower surface dull, light green with patches of fine hair where the lateral veins diverge from the central vein. Their fall color is typically more often deep maroon to rusty red, though on occasion can be brilliant scarlet tinged, all however turning a dull, light brown later in the season, often persisting until spring bud break (marcescent).

[photo of trunk] Bark on mature trees is dark brown to gray with blocky ridges and moderate to deep vertical furrows. In closed canopy forests it is tall and straight with few or no lower branches, but in more open areas, lower branches grow downward creating a large round crown, often close to the ground. Twigs are reddish brown, often glossy.

Fruit: Fruit type: nut

[photo of fruit] Fruit is an egg shaped or elliptic nut (acorn) between ½ to 2/3 inch long, with a deep scaly reddish cap that encloses up to 50% of the acorn.

Notes:

Northern Pin Oak is considered a medium sized tree and rarely attains the over all stature of our native white oak species. However the record pin oak for Minnesota reached 95 feet in height and was nearly 4½ feet diameter at breast height, but due to its age and advanced heart rot, succumbed to a wind storm a few years ago. A common oak species throughout central and southeastern Minnesota, it is noted for its tolerance of dry, sandy or rocky soils associated with savanna and dry prairie margins and is highly fire adapted as well. It can also be found in more mesic wooded uplands which is the preferred habitat of Northern Red Oak (Quercus rubra), with which it is often confused. They share many over lapping characteristics and can be a challenge to distinguish by even well trained foresters. The best identifiers are Pin Oak's shiny upper leaf surface combined with typically deeper, broader, rounded leaf sinuses, its small, ellipsoid shaped acorn and its deep cap. Immature acorns are also frequently visibly striped with darker bands. It can also very difficult to distinguish from Black Oak (Q. velutina), which is perhaps even more tolerant of dry sandy soils, though their ranges only overlap in Minnesota's extreme southeastern counties. While Black Oak's leaves are also shiny on the upper surface, they tend to have more squarish lobes and often have fine, fuzzy hairs across the lower leaf surface that rub off easily to the touch. Black Oak acorns also tend to be rounder and the cap typically covers 50% or more of the nut.

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More photos

Photos by K. Chayka taken in Ramsey County. Photos courtesy Peter M. Dziuk taken in Anoka and Ramsey counties.

Comments

Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Brad - Edina
on: 2014-07-29 23:13:26

I'm currently considering adding the Northern Pin Oak to my landscape. I know that this tree has a fibrous root system, but should I be concerned about it being an invasive? Will it break-up concrete or send large hard roots out into the lawn after several years? Any assistance you can provide would be greatly appreciated. Thank you, Brad

Posted by: K. Chayka
on: 2014-07-30 08:45:25

Brad, northern pin oak is a wonderful yard tree - it is not planted enough. It does require a lot of sun and planting it too close to any hard surface, like a sidewalk or driveway, can (many, many years from now) impact it. And no, it does not root sucker.

Posted by: Tom V - Hennepin
on: 2017-04-07 16:14:13

Can northern red oaks and northern pin oaks be reliably distinguished only by marcescent leaves? I've observed a number of trees that seem to have good examples of red oak leaves and pin oak leaves on the same branch. Is this an indicator of hybridization? The same woods also has some oaks with all leaves like the typical northern red oak leaf. I'm curious if these trees are exceptions or typical northern red oaks.

Posted by: K. Chayka
on: 2017-04-07 19:48:45

Tom, leaf shape for both species can be quite variable so you should inspect several to get a consensus. A hybrid would likely have leaves shaped intermediate between the parents, rather than like some of each parent mixed on a branch.

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