Water oak (Quercus nigra): what the agencies record
What the USDA Forest Service handbooks and plant database record for water oak: the Coastal Plain range, size and growth, its use as a southern street tree, red oak group wood figures, green weight, and the borers, root rot and mistletoe the handbook names.
Checked against the sources at the bottom of this page on October 9, 2026. Rules, fees and pay change: the source has the last word.
This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.
At a glance
| Item | What the source records |
|---|---|
| Scientific name | Quercus nigra L. in USDA PLANTS, beech family |
| Other names | Possum oak and spotted oak (Silvics) |
| Native status, USDA PLANTS | Native in the lower 48 states |
| Size, Silvics | Can grow to 38 m (125 ft) on a site index range of 18.3 to 33.5 m (60 to 110 ft) at base age 50 years; the handbook calls it a medium-sized, rapid-growing tree |
| Roots, Silvics | A shallow, spreading rooting habit |
| Green weight of the wood, NRS-38 | 64 lb per cubic foot, without bark |
Native range and sites
The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) says water oak is found along the Coastal Plain from southern New Jersey and Delaware south to southern Florida, west to eastern Texas, and north in the Mississippi Valley to southeastern Oklahoma, Arkansas, Missouri and southwestern Tennessee. It describes the tree as commonly found along southeastern watercourses and lowlands on silty clay and loamy soils, often abundant as second growth on cutover lands, and it says water oak is also planted widely as a street and shade tree in southern communities. On low flats with poorly drained clay soils the handbook says tree form and quality are poor, and it adds that water oak can survive on moist upland sites.
The chapter lists dozens of associated trees, including willow oak, laurel oak, Nuttall oak, white oak, sweetgum, American elm and loblolly pine. It classifies water oak in the bottom-land cover type Willow Oak, Water Oak, Diamondleaf Oak (Society of American Foresters type 88).
Flowers, fruit and growth
Silvics says water oak is monoecious, with male flowers in hanging catkins and female flowers in few-flowered clusters on the same tree, developing shortly before or with the new leaves. The acorn matures about September of the second year. The handbook says late frosts after the leaf buds open easily kill the flowers, after which the trees defoliate and develop new leaves but do not produce a second crop of flowers.
On growth, the handbook says water oak prunes itself slowly and develops a straight, slender main trunk. On favorable sites it can add 15 to 30 cm (6 to 12 in) of diameter over a 10-year span. In the 36 to 46 cm (14 to 18 in) diameter class it can add 7.8 cm (3.1 in) over a 10-year span, and in the 51 to 71 cm (20 to 28 in) class 7.4 cm (2.9 in).
Wood
Silvics says water oak is particularly suited for timber, fuel, wildlife habitat and environmental forestry, and that its veneer has been used successfully as plywood for fruit and vegetable containers. The Wood Handbook (FPL-GTR-282, 2021) groups it in the red oak group of the Eastern states; what it says about that group is set out once on the northern red oak page. Table 5-3b has a separate water oak row, shown below.
| Wood Handbook Table 5-3b | Specific gravity | Modulus of rupture (lbf per square inch) | Side hardness (lbf) |
|---|---|---|---|
| Green | 0.56 | 8,900 | 1,010 |
| At 12% moisture content | 0.63 | 15,400 | 1,190 |
The Wood Handbook states that specific gravity is based on oven-dry weight and the volume when green or at 12% moisture content. The green weight of the wood without bark is in the NRS-38 table, the same figure used in the log weight calculator.
Diseases, insects and damage the handbook names
Silvics (1990) says the natural enemies of water oak are primarily insects and microorganisms.
- Insects. Trunk borers (Enaphalodes and Prionoxystus species) and leafhoppers (Erythroneura species).
- Diseases. The more noticeable ones listed are rusts the handbook calls cone rusts (Cronartium species), a root rot (Ganoderma curtisii), and trunk canker and heart rot caused by a variety of organisms. The guide on Ganoderma covers that decay group.
- Mistletoe. Water oak is described as susceptible to parasitism by mistletoe (Phoradendron flavescens); see mistletoe on trees.
- Chemicals and air pollution. The handbook says some herbicides are toxic to water oak and that the species is highly susceptible to air pollution, probably to sulfur dioxide in particular.
The guide on reporting a pest in the United States and the Canada reporting page give the offices that take sightings of regulated pests. Who may apply pesticides is in pesticide licences by country.
Sources
- USDA Forest Service, Silvics of North America, Volume 2 Hardwoods (Agriculture Handbook 654, Burns and Honkala, 1990), Quercus nigra chapter by Vozzo, read October 9, 2026
- USDA Forest Service, Forest Products Laboratory, Wood Handbook (FPL-GTR-282), 2021, chapter 2 and Table 5-3b, read October 9, 2026
- USDA Forest Service, Northern Research Station, Research Note NRS-38, Miles and Smith, 2009, Table 1A, read October 9, 2026
- USDA Natural Resources Conservation Service, PLANTS Database, profile data for Quercus nigra (symbol QUNI), read October 9, 2026