Post oak (Quercus stellata): what the agencies record

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 stellata Wangenh. in USDA PLANTS, beech family
Other names	Iron oak (Silvics); the chapter also covers sand post oak and Delta post oak
Native status, USDA PLANTS	Native in the lower 48 states
Size, Silvics	In the Southeast mature trees are 15.2 to 18.3 m (50 to 60 ft) tall and 30 to 61 cm (12 to 24 in) in diameter at breast height; maximum height rarely exceeds 30 m (100 ft) and diameters above 122 cm (48 in) are uncommon; in the extreme western part of the range mature trees are seldom larger than 9 to 12 m (30 to 40 ft) tall
Growth, Silvics	A slow-growing, medium-sized oak considered drought resistant
Green weight of the wood, NRS-38	64 lb per cubic foot, without bark

Native range

The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) calls post oak a medium-sized tree abundant throughout the Southeastern and South Central United States, where it forms pure stands in the prairie transition area. The range extends from southeastern Massachusetts, Rhode Island, southern Connecticut and extreme southeastern New York, including Long Island, westward. The chapter also recognizes varieties: it says Delta post oak (Quercus stellata var. paludosa) is found in bottom lands of the Mississippi River in western Mississippi, southeast Arkansas and Louisiana and west to east Texas. The range reaches from the humid East to semiarid parts of Oklahoma and Texas.

The tree typically occupies rocky or sandy ridges and dry woodlands on a variety of soils. The wood is very durable in contact with soil and used widely for fence posts, which the handbook gives as the origin of the name.

Flowers and acorns

Silvics says post oak is monoecious, with male and female flowers in separate catkins on the same tree appearing at the same time as the leaves, usually beginning in March in the South and extending through May further north. Male catkins are pendant and 5 to 10 cm (2 to 4 in) long. The acorns mature in one growing season, drop from September through November, are 13 to 19 mm (0.5 to 0.75 in) long and are set in a cup one-third to one-half their length. The handbook says late freezes after flowering and leafing starts may cause seed crop failures, and that weevils destroying acorns hamper regeneration.

Roots and drought

The handbook says post oak seedlings have especially thick taproots, usually exceeding the shoot diameter, but that overall root development is less than that of northern red, scarlet, white and blackjack oak. Seedlings were found to be the most drought resistant of four Missouri oaks, primarily because of greater drought tolerance of their leaf and root cells, and in Alabama post oak was the least tolerant of flooding of all species tested. On sites with a tight clay subsoil, seedlings become established but grow slowly and most roots develop above the clay.

Uses beyond wood

Silvics calls post oak a valuable contributor to wildlife food and cover, with acorns important in the diet of wild turkey, white-tailed deer, squirrels and many other rodents, and says it is often used in urban forestry as a shade tree for parks and is planted for soil stabilization on dry, sloping, stony sites. It adds that large trees are difficult to transplant and do not tolerate compaction or removal of soil in developments.

Wood

Silvics says the wood, commercially called white oak, is classified as moderately to very resistant to decay, and lists railroad ties, lathing, siding, planks, construction timbers, mine timbers, trim molding, stair risers and treads, flooring (its highest volume finished product), fence posts, pulp, veneer, particle board and fuel. The Wood Handbook (FPL-GTR-282, 2021) describes the white oak group on the white oak page, and its Table 5-3b has a separate post oak row, shown below.

Wood Handbook Table 5-3b	Specific gravity	Modulus of rupture (lbf per square inch)	Side hardness (lbf)
Green	0.60	8,100	1,130
At 12% moisture content	0.67	13,200	1,360

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 post oak is susceptible to most insects, diseases and pollutants that threaten other oaks.

Defoliators. Leafrollers, tent caterpillars, the gypsy moth (also called the spongy moth, see the spongy moth page), sawflies, leaf miners and skeletonizers may cause growth losses and, when repeated, mortality.
Other insects. Aphids, lace bugs, scales, gall wasps and mites on the foliage, and carpenterworms, borers, beetles, twig pruners, white grubs and cicadas on trunk, twigs and roots, some of which cause defects the handbook says render the wood unfit for many commercial purposes.
Chestnut blight fungus. Cryphonectria parasitica is named as causing many defects as well as mortality to post oak throughout its range.
Oak wilt. A vascular disease the handbook says is prevalent mostly north of the 35th parallel, but not to the same degree as on red oaks; see oak wilt.
Root and seedling fungi. Soil-inhabiting fungi that cause damping off of seedlings, powdery mildews on nursery seedlings, and Texas root rot (Phymatotrichum omnivorum), which attacks mainly oaks planted on old farm fields or in subdivisions.
Decay fungi and mistletoe. Decay fungi cause cankers, rots and discoloration of stem and roots. Several mistletoe species are often found on branches and trunks, where infected branches may be stunted and eventually die, but trees usually are not killed; see mistletoe on trees.
Pollutants. The handbook says nonpoint source pollutants near large cities cause twigs of many oaks to die back or kill the trees, and names sulfur dioxide, fluoride, ammonia and some herbicides as probable agents while noting the specific diagnosis is usually difficult.

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.