Quercus nigra aka Water Oak

Quercus nigra, or water oak, belongs to the beech family. This red oak grows in the central and eastern United States. Its range includes New Jersey, Florida, Texas, and Oklahoma. It grows in flood plains, stream banks, and drier woods. Trees grow fast and may live just 30–50 years. Garden trees reach 50–80 feet (15–24.4 m) tall. Their crowns spread 50–70 feet (15–21.3 m) wide. Some trees reach 100 feet (30.5 m), beyond that usual range.

The crown starts cone-shaped and becomes broad and round. Young bark is smooth and brown. Age makes it dark, rough, and deeply ridged. Thin twigs have a red-brown hue and pointed buds. Simple leaves grow in an alternate pattern along each twig. Their shape varies from narrow to broad and spoon-shaped. Some have small lobes, with or without bristle tips. Leaves look blue-green above, with paler, hairy patches below. Fall brings yellow or brown tones before leaves drop. In the Deep South, some leaves stay through winter.

Small flowers appear in April, with little show for gardeners. Male flowers hang in catkins; female flowers form short spikes. Dark acorns take two growing seasons to ripen. Each nut has a shallow cap covering about one-third. Acorns fall from September to November in North Carolina. Squirrels and other mammals eat them. The tree also hosts moth and butterfly larvae. Leaves and acorns create litter beneath the crown. Fallen nuts can stain paving through fall and winter.

Water oak grows best in full sun and rich, acidic soil. It also accepts part shade, clay, sand, and loam. Moist to wet sites suit it, including low garden spots. It tolerates drought, but very alkaline soil can cause chlorosis. Sources list USDA zones 6–9, with Florida guidance extending into 10A. The RHS gives it a UK hardiness rating of H4. Its size suits parks, large lawns, and broad shade plantings. People also use its wood for fuel, veneer, and plywood.

Weak limbs can break under wind, snow, or ice. Early pruning helps build a stronger branch frame. Trunk decay and cankers can shorten its life. Oak wilt may kill it; mildew and root rot also occur. Scale, borers, leaf miners, and caterpillars may attack it. Acorns are edible only after processing removes their bitter tannins. Untreated nuts can cause gut pain and other poisoning symptoms. They can also block the gut. The RHS warns that eating this plant can harm dogs.