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Jack Oak (Quercus ellipsoidalis)

Also known as northern pin oak, Hill's oak, upland pin oak.

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A species of oak mostly found in a small region of the upper midwestern U.S. Unlike the name suggests, probably most closely related to species other than the pin oak (Quercus palustris).

USDA Plants Profile for Quercus ellipsoidalis

Fire Effects Information System (FEIS) Article for Quercus ellipsoidalis

Description & Identification

A medium-sized deciduous tree to 70 feet (21 m) in height. Crown is irregular and often open and thin. Often retains stubs of lower dead branches. Leaves have 5-7 lobes; mature trees have deep sinuses between lobes, extending more than halfway to the leaf's midrib.

Root system is extensive, consisting both of a deep taproot and widespreading and deep lateral roots.

Similar Plants

Northern Red Oak (Quercus rubra)
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Pin Oak (Quercus palustris)
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Limited to dry, upland sites with acidic, sandy soils and little organic matter. Within its range, it is the most drought-tolerant of all oaks of the red oak group. Common on sand plains of glacial origin, and also on sandstone hills.

On sites capable of supporting more shade-tolerant vegetation, functions as a pioneer species and is replaced by other oaks including white, black, northern red, and bur oaks, as well as by eastern white pine. However, persists indefinitely on nutrient poor, dry sites where other hardwoods cannot survive.

Common in habitats that burn regularly. Often forms a stable community together with jack pine on sites with too regular and/or too severe fires for other tree species to survive.

Life Cycle

Seedlings quickly establish a deep taproot.

Trees begin producing seed around 20 years of age; acorns take two seasons to mature. Good seed crops are produced every 2-3 years; in other years, most of the seed is destroyed by weevils. Seeds are distributed mostly by squirrels and blue jays, and by gravity on hillier sites.

Seed requires a period of cold dormancy, and germinates in the spring. We could not find any record of seed banking and seed of this species probably does not survive more than one year.

Mature trees are usually unaffected by low-intensity fires, but young trees with small diameter stems can be killed by fire, and severe fires can kill mature trees. However, trees that are top-killed resprout vigorously.

This species is most closely related to scarlet oak (Quercus coccinea), which generally does not overlap with it in range.

It is also related to northern red oak (Quercus rubra) and black oak (Quercus velutina); both of these species overlap more with this one in range, and can form hybrids.

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