Quercus falcata, the Southern Red Oak, is one of the commonest upland oak species in the Central Piedmont of North Carolina. It is a member of the red oak group, which is characterized primarily by the bristles at the end of the leaf lobes, and by acorns that require two years to mature. The Southern Red Oak has a prodigious array of leaf patterns, a characteristic that is difficult to appreciate in the spring and summer when the leaves are high on the tree, but is conspicuous when the leaves are directly under foot in the late fall and winter.
The species name falcata is descriptive of the majority of mature leaves, falcate meaning curving and tapering gradually to a point. The fall leaves pictured below are easily recognized, and are most commonly associated with the Southern Red Oak. They are shown with the reverse side up to illustrate the tawny, light color of the underside, which remains fuzzy to the touch even after the leaf dies and is shed.
This oak has quite a repertoire of intermediate shapes and sizes that are not always immediately recognizable as Southern Red Oak. A few of them are shown below, but there are many more than this photo illustrates. These leaves are shown topside up.
Small, immature trees have very different leaf patterns, most of which could be described as tri-lobed, with the tips of the leaves having a rounded, blunt appearance. Completely ovate leaves can also be found, a shape not well known or described. The leaves below came from a young, 15 foot Southern Red Oak , and all the leaves were taken from the same branch.
The leaf shapes illustrated above are not restricted to saplings, but can sometimes be seen on trees of medium height. The ovate leaves on the lower right in the photo still have the characteristic bristles, approximately where the three lobes would be if they were present. See below.
Blackjack Oaks, Quercus marilandica, are much less common than Southern Red Oaks, but do appear sporadically in the same areas. Their leaf shapes are much less diverse, but can sometimes be confused with the immature Southern Red Oaks. A few representative Blackjack Oak leaves are pictured below.
Three tri-lobed leaves from a young Southern Red Oak are at the top of the next picture, with two Blackjack Oak leaves below them. These leaves were taken from young trees directly adjacent to each other, with some of the branches intertwined. It is easy to see how they could be confused.
While the leaves of the Blackjack Oak pictured above are coarsely lobed, they are usually shallower than the lobes of the Southern Red Oak above. In addition, the tips of the Blackjack Oak leaves are wider proportionally than the Southern Red Oaks.
The Pagoda or Cherrybark Oak (Quercus pagoda) has probably the most difficult leaf to distinguish from the Southern Red Oak. In fact, at one time the Pagoda Oak was classified as a variety of the Southern Red Oak. Below are typical leaves of the Pagoda Oak.
Below is a comparison between two Southern Red Oak leaves (on the left) and two Pagoda Oak leaves (on the right).
The base of the Southern Red Oak leaves tend to be rounded while the base of the Pagoda Oak leaves tend to be sharp and angular. The Pagoda Oak leaves also tend to be more symmetrical, with lobes often opposite each other, while regular symmetry is not common in Southern Red Oak leaves. When distinguishing these two trees, it helps to look at many leaves rather than just a few as pictured above.
Leaf shape depends on many variables and is seldom used alone to distinguish tree species. Location on the tree (sun vs. shade), soil type and habitat, rainfall or lack of it, and most importantly genetics, all affect leaf shape.