How to Identify Oak Leaves

Distinguish oak trees from other tree species. Oaks, all of which belong to the genus Quercus, are broad-leaved trees that grow in temperate climates throughout the earth. More than 600 species of oak have been discovered, of which 55 are found in the United States. Because there are so many species of oak in the world, it can be difficult to find common characteristics. However, the following characteristics of oak trees have been found:

• The acorn is the most recognizable feature of the oak tree. If the tree produces acorns, it is an oak tree.
• Lobed leaves are leaves that have rounded or tapered sections that protrude from the leaf veins. Although the leaves of some species of oak are not lobed, all oak leaves are generally symmetrical through a distinct central vein.
• The bark consists of small scales. Although slightly different, oak bark is usually composed of small, hard, scaly flakes. This bark pattern differs from the broad, flaky patches of pine or the wallpaper of birch, and has more grooves and fissures. ^[1]

Observe the tip of the leaf lobe to identify two groups of white oak and red oak. The leaf lobes are the parts of the leaf that protrude from the center to the sides of the leaf blade like the wings of a star. White oak has rounded leaf lobes, while red oak has pointed leaf lobes. This is an important distinction that cuts the tree species in doubt by half that you are identifying. ^[2]

• In the red oak group, the leaf veins run all the way to the edge of the leaf and form an acute angle. ^[3]

In terms of geographical location. Each geographic region has its own species of oak that are often significantly different from other regions. Depending on the geographical area of the earth, the species of oak that you are likely to encounter will vary greatly, because it is very rare that oak trees that grow on the east coast can be found on the west coast, or oak species. living in the south reappears in the north, etc. In general, you can identify the region you live in by a few criteria as follows (examples here are in the continental United States):

• General Location – Northeast, Southeast, Midwest, Northwest, Southwest
• Inland or coastal area
• Mountains or plains ^[4]

Count the leaf lobes. The leaf lobes are the protrusions on either side of the leaf blade from the midrib. If possible, compare multiple leaves to find the average number of lobes. A few species such as willow oak have no lobes at all, but most oak species have multiple lobes. ^[5]

• When determining the number of leaf lobes, you should count at least 4-5 leaves, as this will be helpful when you refer to the manual.

Consider the notches between the leaf lobes. Observe the notches between the leaf lobes to see if they are shallow or deep. White oak often has randomly alternating shallow and deep notches, while red oak can have very deep notches or no notches at all.

Observe the change in leaf color in the fall. Evergreen oaks have glossy, dark green leaves year-round, but most oak species change color in the fall. Some species such as scarlet oak (Quercus coccinea) show off their vibrant colors in the fall. White oak and chestnut oak have brown leaves when they change color.

• In the summer, observe whether the leaves are light or dark green, glossy or not, to identify the oak species.

Estimate the overall size of the leaves. The evergreen oak group and some red oak species such as scrub oak have small leaves, while most red oak species and most deciduous white oak species have much larger leaves (at least 10 cm). This is one of the most important distinguishing features among similar-shaped oaks.

Identify oak trees you don’t know with the U.S. Forest Service’s guidebook. You can use the collected data to identify oak trees according to the manual. There are dozens to hundreds of different types of oak, and you can’t memorize them all. Use the criteria above to narrow down the scope, then use your guidebook to find the type of oak you’re considering. You can view a collection of commonly encountered oak species below, or consult the U.S. Forest Service’s Guide.

• Find the right section in the book. Most guidebooks are divided into two groups for red oak and white oak.
• Narrow the scope of the definition to a specific area. A good guidebook will have maps for each tree species.
• Once you’ve found a list of possible oak species, look at the pictures of each tree to identify it.