The Virginia Department of Forestry lists many types of oak trees as being native to the state. Oaks such as the water oak, blackjack oak, live oak, chestnut oak, post oak, willow oak and white oak are some of the oaks you will encounter while traveling through Virginia. To tell which oak you have found, you need to distinguish from one another such characteristics as height, leaves, bark and the acorns these oaks produce.
Estimate the heights of the oaks you find in Virginia. Among the smaller oak trees that grow there are the blackjack oak, a tree with an average height between 20 and 30 feet, and the sawtooth oak, which rarely exceeds 45 feet. The taller oaks in Virginia include types that come close to 100 feet tall, such as willow oak and laurel oak. Some oaks, such as live oak, will have a spreading canopy as wide as the actual height of the specimen.
Inspect the leaves of Virginia's oaks, paying close attention to their sizes and shapes. The identification keys related to oak leaves include the length and width of the leaves, the number of lobes the leaves possess and whether or not the lobes have rounded or pointed edges. For instance, the pin oak has 3- to 5-inch-long leaves that may be as wide as 5 inches at some points. There will be from five to nine lobes on the leaf, and these lobes will have points on them. Conversely, the lobes of the post oak have rounded edges, with the normal post oak leaf having five lobes.
Look for trees with leaves that do not match the stereotypical shape of lobed oak leaves. Virginia has species such as willow oak and laurel oak with long narrow leaves. Live oak has oblong evergreen foliage, while the leaves of chestnut oak are oblong with many coarse teeth.
Examine the acorns that emerge on the twigs and finally fall off the oak species growing in Virginia. Study their lengths and pay heed to their caps, where they attach to the twigs. Water oak will have an acorn that is dark brown, a half-inch long and a cap covering about a third of the nut. The swamp chestnut oak has a longer acorn, about 1.5 inches in length, with an egg shape and a cap resembling a bowl. These differences in the fruit of the oak trees can often help you recognize specific species.
Observe the bark of the Virginia oaks, looking for distinct variations in color and texture. A case in point is the black oak, which gets its name from having deeply furrowed, almost black bark with an inner bark that will be a yellow-orange color. Live oak bark is a dark shade of brown and only somewhat furrowed, with the older individuals developing a dark blocky covering.