Oak trees are a member of the genus Querus, which contains about 600 different species all over the world. However, unless you are a trained botanist, it can be difficult to ascertain which particular species you are looking at. How can you identify various types of oak trees just by sight alone? In the following article, we will examine the most popular types of oak trees found in North America and explain what the differences are that make each tree identifiable to the untrained eye.
In many species of oak trees, the leaves are spirally arranged with a lobed outer margin, while some species have serrated leaves or are entirely smooth. Most oaks will flower and produce fruit in the springtime in the form of an acorn, which is a nut in a cup-like structure which takes 6-18 months to mature, depending on the type of species. The “live oak” group has evergreen leaves and is not distinctive, but can be found in many areas throughout North America.
The Black Oak is a common tree located throughout the eastern and Midwestern United States. These trees require moist, rich soil to grow and generally do not live more than 200 years. The leaves of a Black Oak are 4-10 inches in length, oval shaped, with 5-7 bristly-tips. The leaves shapes are variable and with sun, have deep cavities and in the shade, the leaves have shallow pits, the color is a shiny green on top and underneath is pale. Twigs of the Black Oak are reddish-brown or gray-green in color and have hair, buds are large, buff or cream in color, pointed, fuzzy and very angular to the eye.
The Bur Oak is classically witnessed on American savannas and is a member of the white oak family. This particular species of oak can be found through the Eastern US and along the Great Plains and grows in Louisiana, Alabama, Arkansas, Tennessee, Montana, North Dakota, Wyoming, South Dakota, central Nebraska, Texas, and western Oklahoma. The leaf of a Bur Oak is 6-12 inches in length; oval shaped and has many lobes, with two middle sinuses which divide the leaf in half. The lobes near the top of the leaf look like a crown, and are green on top and pale and fuzzy underneath.
The Cherrybark Oak is also referred to as the swamp Spanish Oak, Elliot Oak, bottomland red oak, and more simply the red oak. This particular oak species grows mostly on moist sites and has a much more distinctive and easily identifiable form than a Southern Red Oak. The leaves of this oak are shaped like a pagoda and differ from the Southern Red Oak in that they are more lobed and u-shaped. These particular trees are among the fastest growing in the oak family and can reach heights of 100-130 feet, with a diameter of 36-60 inches.
The Laurel Oak has a long history and is planted in the South for use as an ornamental; it has no particular value and is primarily used for fuel purposes. The largest number and best formed Laurel oaks are located in Florida and Georgia, but can also be found in Virginia and southeastern Texas. The leaves are 3-5 inches long, 1-1 ½ inches in width, thick and shiny on top and pale and smooth underneath. The twigs of a Laurel Oak are slender, light red-brown in color, completely smooth, but with sharp pointy buds with clusters at the ends.
Oregon Live Oaks are commonly found along the Pacific Coast, Columbia, Washington and into some parts of Canada. The tree flowers in late spring throughout March, April, May and June and the flowers emerge from buds on existing twigs and are a pale yellow in color, tinted with green. To identify an Oregon Live Oak, a person will notice the wood is very dense and the leaves are dense, green colored and divided in the middle of the stem and separated into individual, irregularly shaped sinuses, the tree can be found along inland valleys, foothills, slopes and unglaciated and glaciated rocky ridges.
The Overcup Oak is primarily found in swampy areas and can also be referred to as a swamp post oak, swamp white oak and water white oak. The leaves of this particular oak alternate, are 6-10 inches in length, oblong shaped and have 5-9 lobes, with a white underside. The twigs of an Overcup Oak are thin and gray, and look much like those of a white oak, the buds are small, oval shaped and a light brown in color with clustered end buds.
Post Oaks are widespread across the country and primarily found ranging from the eastern to central US. The leaves of Post Oaks are oblong, 6-10 inches in length, with 5 distinctive lobes, with the middle two being square, thick textured, and green on the topside and paler on the bottom. The twigs of this tree are gray or tawny colored and dotted with many lenticels (small, corky pores), multiple buds, and short, blunt, orange-brownish colored stipules.
Pin Oaks are some of the most distinctive in the oak family in that its physical characteristics make it very easy to identify. It has small, thin, dead branches with stick out from the tree like pins from the main trunk. The leaves of a Pin Oak are 3-6 inches in length, oval in shape and have 5-9 bristle-tipped lobes with a deep sinus, with major lobes being u-shaped. The Pin Oak twig is thin, slender, and reddish-brown in color and has lustrous buds which are small, pointy and chestnut brown colored.
The Northern Red Oak is the only native oak tree which extends to the northeast of Nova Scotia, Canada, and can also be found in Minnesota, Nebraska, Georgia, Alabama, Arkansas, North Carolina, Mississippi and Louisiana. The leaves are 5-8 inches long, oblong shaped, and have 7-11 bristly lobes which are uniform in shape, and a dull green on the top and a paler shade of green on the underside. The twigs of a Northern Red Oak, are stout, and covered with hairless scales and can have some frosty looking residue on the tips.
The Scarlet Oak is found from Maine to as far west as New York, Ohio, Indiana, southern Illinois and southeastern Missouri and central Mississippi. The leaves of this oak are simple, 3-7 inches in length, oval shaped and shiny green on the top and hairless, but can have small tufts in vein axils. The twigs are moderately fat, reddish-brown in color with many buds, which are red-brown in color, stout, pointy, slightly angular with frost on the top half.
The Shumard Oak is the largest of all southern red oak trees and only produces acorns every 2-4 years. The leaves of this oak are 4-7 inches long and contain between 4-9 lobes with coarse, bristly tips and are shiny green in color on the top and pale green underneath. Twigs of the Shumard oak are moderately stout, with clusters of buds which measure ¼ inch in length, are grayish-brown in color and can either be smooth or only lightly fuzzy.
The Water Oak is a fast-growing tree, with leaves that are long, narrow and shaped like a spatula. Water oaks are found from New Jersey, to Delaware, Florida, Texas, Oklahoma, Arkansas, Missouri and southern Tennessee. The twigs of the Water Oak are slender, red-brown in color, sharply pointed at the ends and have multiple buds at the tip.
Willow Oaks are commonly found along waterways and grow rapidly and have a long life. These oaks are found in the bottom lands of the Coastal Plain, Texas, Oklahoma, Arkansas, Mississippi, southeastern Missouri, southern Illinois, Kentucky and western Tennessee. The leaves are 2-5 inches in length, and have a willow shape with bristly tips. The twigs are hairless, slender, and olive green in color with many buds at the ends which are reddish-brown and contain sharp points.
With a bit of time and studying, it is possible to go strolling through a forest in the US and identify the native species of oaks found growing there. Oak trees are an important part of the environment and are not only used as fuel, but also are a vital source of food for native wildlife such as deer, ducks and squirrels. Oak trees have long been a symbol of strength and endurance for the US and in November of 2004 through an act of Congress, these majestic beauties became America’s National Tree.