The Water Oak (Quercus nigra) is an oak in the red oak group (Quercus sect. Lobatae), native to the southeastern United States, from southern Delaware and south to the coastal areas of Maryland, Virginia, the piedmont of North Carolina, all of South Carolina, most of Georgia (with the exception of the Appalachian Mountains), all of Alabama, Mississippi, central Florida, and westward to Louisiana and eastern Texas. From there, northward to southeastern Missouri including Arkansas, parts of Tennessee, and extreme southwestern Kentucky. It occurs in lowlands and up to 450 m (1500 ft) altitude.
It is a medium-sized deciduous tree, growing to 30 m (100 ft) tall with a trunk up to 1 m (3 ft) in diameter. Young trees have a smooth, brown bark that becomes gray-black with rough scaly ridges as the tree matures. The leaves are alternate, simple and tardily deciduous, only falling well into winter; they are 3-12 cm (1-5 in) long and 2-6 cm (1/2-2 in) broad, variable in shape, most commonly shaped like a spatula being broad and rounded at the top and narrow and wedged at the base. The margins vary usually being smooth to shallowly lobed, with a bristle at the apex and lobe tips. The tree is easy to identify by the leaves, which have a lobe that looks as if a drop of water is hanging from the end of the leaf. The top of each leaf is a dull green to bluish green and the bottom is a paler bluish-green. On the bottom portion of the leaves, rusty colored hairs run along the veins. The acorns are arranged singly or in pairs, 10-14 mm (1/3-1/2 in) long and broad, with a shallow cupule; they mature about 18 months after pollination in fall of second year.
Water Oak is adapted to wet, swampy areas, such as along ponds and stream banks, but can also tolerate other well-drained sites and even heavy, compacted soils. It grows in sandy soils, red clays, and old fields to the borders of swamps, streams, to bottomlands. Due to its ability to grow and reproduce quickly, the water oak is often the most abundant species in a stand of trees. The tree is relatively short-lived compared to other oaks and may live only 60 to 80 years. It does not compete well and does not tolerate even light shade. Water oak is frequently used to restore bottomland hardwood forests on land that was previously cleared for agriculture or pine plantations.
Hybrids of Water Oak are known with Southern Red Oak (Q. falcata), Bluejack Oak (Quercus incana), American Turkey Oak (Quercus laevis), Blackjack Oak (Quercus marilandica), Willow Oak (Quercus phellos), Shumard Oak (Quercus shumardii), and Black Oak (Quercus velutina)
Water Oak acorns are an important food for White-tailed Deer, Eastern Gray Squirrel, Raccoon, Wild Turkey, Mallard, Wood Duck, and Bobwhite Quail. In winter, deer will browse the buds and young twigs.
Other names include spotted oak, duck oak, punk oak, orange oak or possum oak.