Acorns and life-sustaining mast are critical to deer survival, especially through winter. And that means mast is critically important to deer hunters and rural property owners.
Acorns are also helpful when hunters and landowners are trying to identify what type of oaks are on a property or piece of public-hunting ground. But acorns aren’t on the ground 24/7. In the summer and spring months, you’ll need to rely on leaves and bark patterns to identify oak tree species. And in the winter months, after an oak’s leaves have dropped, you can’t even rely on the color and features of a leaf to help you with tree identification.
That leaves you with bark trivia. How well do you know your bark?
Here’s a quick reference guide for eight of the most prominent oak trees in the U.S. For each oak variety, we’ll list the most common traits of the tree’s composition, its leaves and bark patterns.
The White Oak Group
Trees in the red oak group take two growing seasons to produce a mature acorn, while trees in the white oak group only need one growing season to produce a mature acorn. White oak acorns are considered more palatable to deer and other wildlife due to their lower concentration of tannic acid.
Those who spend time in the woods or aren’t new to deer hunting will recognize the white oak. It’s the most widespread of all oak varieties. It’s particularly dominant in the eastern half of North America from Canada to Florida.
- Short, stocky trunk.
- Strong, thick horizontal limbs.
- Color: light, ash-gray.
- Often the bark is small and narrow, arranged in rectangular blocks or scales.
- Color: ranges from dark green to blue-green in summer, changing to hues of browns, deep reds and orange-red in the fall.
- Shape and Size: Leaves are 4 to 8 inches long with 3 to 4 rounded, finger-like lobes on each side and one at the tip of the leaf.
The bur oak lives more than 200 to 300 years. Some refer to this oak species as a mossycup oak. Like many oaks, it’s difficult to transplant.
- Grows rounded in shape, offering dense shade.
- It’s considered a slow-growing tree, increasing in height by less than 12 inches per year.
- Bark is dark gray or gray-brown.
- Rough and deeply ridged on older trees.
- Leaves are 6 to 12 inches long with 5 to 9 lobes.
- Leaves are separated about halfway down by a pair of particularly deep sinuses.
The post oak is considered a medium-to-large tree. This tree is so common in east Texas it influenced the name of the state’s Post Oak Savannah region.
- The post oak has a compact, rounded crown and a short trunk.
- Typically reaches a height of 50 feet.
- The bark is thick, gray-brown and has narrow, irregular fissures.
- Older trees tend to have scaly ridges on the trunks.
- Usually 4 to 6 inches long and nearly as wide, the post oak leaf typically has five lobes, no bristle-tips. Often the lobes form a cross shape on the ends.
- The leaves are dark green and somewhat leathery.
This is an oak that can’t survive in colder climates. It’s limited to Hardiness Zones 7 through 10. The live oak grows rapidly when it’s young and can live to be centuries old.
- The live oak has a massive spread of 60 to 100 feet at maturity.
- It’s common for the live oak to grow to 50 feet tall.
- It has a short, stout trunk.
- Limbs often touch the ground in open-growth settings.
- The bark is dark brown. Like most oaks, it's rough in texture.
- The bark will develop very thick, interlacing ridges and deep furrows as the tree ages.
- Leaves are 2 to 4 inches long and 1/2 to 2 inches wide.
- Leaves are evergreen, thick and leathery, smooth and glossy.
- Leaf shape is oval, oblong or elliptical in shape.
- Dark green in color, the leaf’s underside is pale and silvery-white.
U.S. Hardiness Zones
U.S. Hardiness Zones. Image: Arbor Day Foundation
The Red Oak Group
Trees in the red oak group take two growing seasons to produce a mature acorn, while trees in the white oak group only need one growing season to produce a mature acorn. Red oak acorns are considered bitter and less palatable to deer and other wildlife due to their high concentration of tannic acid. However, red-oak acorns have a higher nutritional value and last through the hard winter months.
Northern Red Oak
Landscapers love this tree. It’s considered a great street tree. This oak prefers moisture but has some drought tolerance. This oak can grow as much as two feet per year for 10 years.
- Grows in a rounded shape.
- Typically features a dense crown.
- Considered among the fastest-growing oaks.
- Like other oak species, the bark on young trees is smooth and gray-green in color.
- As the tree ages, the bark breaks up, forming firm, elongated, flat-topped ridges.
- Typically the bark’s ridges are marked lighter in color than the furrows.
- Leaves are 5 to 9 inches long, 4 to 6 inches wide, with 7 to 9 lobes.
- Lobes are sparsely toothed and bristle-tipped.
- At maturity, leaves are thin, dark and green. They have a shiny appearance.
You’ll often find water oaks, as you might expect, along ponds, the banks of streams, swampy areas and heavy, compacted soils that don’t drain well. That’s not to say they can’t handle drier ground. They can.
- Often leaves will not fall until late winter.
- Leaves are 2 to 8 inches long, 3 to 4 inches wide and mostly spatulate, meaning they’re broad and rounded at the top and narrow and wedged at the base.
- They can be 3-lobed at the apex or variously lobed (typical for sprouts and young trees).
- Tops of the leaves have a richer green to bluish color, while the bottom of the leaf tends to be a pale bluish-green.
Pin oaks are known for their tolerance of wet conditions. Regionally, some call the pin oak a swamp oak. This oak is a fast grower and can be expected to increase in height by 24 inches per year.
- A young pin oak is pyramid-like in shape but — as it grows older — it takes on more of an oval shape.
- The tree develops a single, central trunk from ground to tip.
- Branches on the lower third of the tree angle downward.
- Bark is light brown, smooth and shiny, becoming gray-brown as the tree ages.
- Grooves are shallow with closely flattened scales coming with age.
- Leaves are 3 to 6 inches long with five lobes (although sometimes 7 to 9) separated by very deep sinuses.
- In summer, leaves are dark green and glossy. By fall, leaves will turn scarlet and bronze.
The black oak can grow to be 100 feet high. They do well in poor growing conditions thanks to long, prominent tap roots. It’s a hardy tree, but does tend to suffer from decay.
- The shape is irregular, and the tree is often thought to look unruly.
- Typically the black oak reaches 50 to 60 feet in height.
- The black oak gets its name from a nearly black bark.
- The inner bark is a yellow or deep orange in color.
- The bark furrows vertically with horizontal breaks. It’s very rough and thick.
- Leaf size is 5 to 9 inches long, and leaves have 5 to 7 irregular bristle-tipped lobes.
- In early spring, the black oak has red leaves that emerge from winter buds.
- By summer, leaves become a glossy green.
What’s Next: Learn Which Acorns Deer Like Best
Learn which acorns deer like best and why in our blog post about acorn characteristics, tasting notes and the most common native oaks in the U.S. Each acorn type — white and red — plays a vital role in sustaining deer and other wildlife through harsh winter months.
Featured photo: Csaba Nagy, Pixabay