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Water Oak (Quercus nigra L.)

Also known as possum oak.

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Water Oak

Summary

A red oak of wet areas in the south, whose tardily-deciduous leaves have a distinct, spatula-like shape.

Range - Expand

LegendColor
Native
Native or Not Present

This map is based on our research. We have checked its accuracy to Level 3 ecoregions. Although this plant occurs somewhere in each of these regions, it may only occur in a small part of some or all of them.

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Habitat

Primarily found in bottomland forests in the southeastern U.S., on levees, ridges, and elevated margins of swamps and rivers. Usually found on sites that flood deeply and frequently but drain quickly; also found on uplands to about 1,000 feet (300m) on sites that remain consistently moist.

Grows best on well-drained soils; grows poorly on flat sites with poorly-drained clay soils. Primarily found on inceptisols.

Tolerates several weeks of flooding each season, and can tolerate longer flooding of up to several months if it does not occur regularly.

Usually found in mid-successional stages, invading pine forests where those forests are protected from fire. Can colonize abandoned fields on fine-textured loess soils. Usually eventually replaced by other species on more favorable sites, but it is ideally suited to grow on ridges less than 5 feet (1.5m) above floodplains, and it can persist as a climax species on such ridges.

Life Cycle

Water oak is a fast-growing, short-lived tree.

Seedlings emerge late in spring, adapted to avoid spring flooding. Seedlings are initially poorly-equipped to handle flooding. The large seeds give seedlings the ability to survive low-light conditions, drought, and herbivory. However, seedlings require consistent moisture for optimal growth.

Under ideal conditions, seedlings can grow 2 feet per year, rapid for an oak. Seedlings suppressed by shade but with enough light to survive, may grow as slow as 2 inches per year.

Trees begin producing seed around 20 years of age. Good seed crops are usually produced every other year. Acorns are distributed by water, gravity, and animals, including squirrels and blue jays.

Trees of all ages will resprout vigorously from the root system if top-killed.

This species has an unusually short lifespan for an oak; we found a variety of sources report its typical lifespan as 30-50 years, 40-60 years, and 60-80 years; at any rate all of these are shorter than most other red oaks of similar size. Trees can be killed by insect damage and disease, often provoked by a period of drought. Individual trees may live longer, perhaps to 150 years, although uncommonly.

Uses

Water oak is used effectively to reforest bottomland sites in the southeast where the land has been cleared for agriculture. Trees perform well on such sites whether seeded or planted.

It is occasionally used as a shade tree, where it is valued for the distinct shape of its leaves and its tendency to retain green leaves longer than most oaks, leading it to appear nearly-evergreen in late fall to early winter. Its use in landscaping is limited by its being weak-wooded and susceptible to limb breakage. Although occasionally used as a street tree, it is not well-suited to this purpose, in part because it has poor pollution tolerance. It is primarily used in landscaping in the south. and only occasionally planted near its northern range limits.

Although not among the most important timber species, its wood is similar to other trees of the red oak group, and often sold along with them.

This species belongs to the red oak group, all of which are closely-related. Within this group it may be closest-related to the Darlington oak (Quercus hemisphaerica), followed by laurel oak (Quercus laurifolia).

However, it is actually more likely to hybridize with other, less-closely-related members of this group, including southern red oak (Quercus falcata), bluejack oak (Quercus incana), willow oak (Quercus phellos), turkey oak (Quercus laevis), shumard's oak (Quercus shumardii), and black oak (Quercus velutina). All of these hybrids have been found in the wild on multiple sites and some are relatively widespread through the overlaps of these species' ranges.

Water Oak | The Wood Database (About This Site)

Water Oak | Fire Effects Information System (FEIS) (About This Site)

Quercus nigra (Water Oak) | USDA PLANTS Database (About This Site)

Quercus nigra (Water Oak) | Missouri Botanical Garden Plant Finder (About This Site)

Water Oak | Virginia Tech Dendrology Factsheets (About This Site)

Water Oak | Silvics of North America (About This Site)

Quercus nigra | Biota of North America Project (BONAP) (About This Site)

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