One of the most common oaks I see in the Atlanta area is the water oak, or Quercus nigra. This oak is in the red oak subgenus. Common names for this tree are possum oak and spotted oak. It is said that this tree is often hollow by its 40th year, resisting rot and diseases poorly compared to most oaks. The tree is named for how opossums are often found in the tree’s hollow, how water often accumulates in the hollow and pours from it when the tree is cut down, and how spots or splotches can be found on the upper trunk of older trees. It is interesting how a tree is named.
The crown of the water oak has ascending limbs which form a rounded top. The trunk is gray, 
slender and almost smooth when young. With age it becomes darker, develops furrows with scaly ridges, and can become over 3 feet in diameter. The upper trunk remains smoother with white spots, longitudinal streaks, and faint horizontal bands. The tree’s growth of 24 inches or more per year makes it popular as a shade and landscaping tree, but this fast growth makes it more weak-wooded and prone to damage by wind, snow and ice than most other oaks. The tree most often grows to about 80 feet tall and 60 feet wide, but it can grow to 120 feet in inland areas where weather conditions tend to be less severe. Pruning is important to prevent problems of poor crotch attachment where limbs can split and sagging limbs can break.
Leaves of a water oak are 
semi-evergreen, keeping most leaves through winter. Leaf loss is variable, with some trees losing maybe 70% of leaves and other trees (in the same area) losing only 30%. The shape of a water oak leaf in the sun is consistently oblong, and it appears similar to a spatula or turkey foot. Leaves found in the shade can be twice as large and have variable shapes. A leaf in the sun typically is 1 to 4 inches long and up to 2 inches wide. It is broad and rounded near the apex, and narrow and wedged at the base. The points where the leaf is broadest and the apex tip form shallow lobes that have distinct bristles when young, but these bristles are often not observed on older leaves. Many people imagine the leaf tip having a drop of water hanging from the end. Leaf color is dull green to bluish green on top, and paler green beneath. 
Veins on the bottom of the leaves are tomentose. Leaves are attached to twigs by petioles that are ¼ inch or less, and they are stout and flattened. Twigs are slender and smooth, with a star-shaped pith.
Minimum flowering age for the water oak is 20 years. Male flowers are catkins, female flowers are on spikes, and they occur on the same tree. The fruit is an acorn, and it may appear singly or in a pair. The acorn is ovid-shaped with a pubescent (hairy) tip, and it is about ½ inch long. The acorn is light brown to nearly black, and it has a shallow cap that is wooly rather than scaly. The cap attaches to the twig by a short peduncle. The acorn matures in the second year, which is typical of oaks in the red oak subgenus.
The water oak is common in the Atlanta area. It is easier to identify than many oaks, and has an interesting name.
