Black oaks are one of the lesser-known trees of the oak family. However, just because a tree isn’t particularly valuable in the lumber industry, doesn’t mean it is not integral to wildlife.
The black oak is a tree (sometimes shrub) in the oak species with much darker bark. Though most oaks are fairly easy to recognize by their foliage and acorns, you may have to look a little harder to discover the characteristics of black oak.
In the spirit of tree identification, head on over to 101 Types of Trees to learn more about our woody friends!
We’ve also prepared articles on the Chestnut Oak, Northern Red Oak, Scarlet Oak, and White Oak as well![toc]
The black oak is part of a large family of varying trees. Sometimes deciduous, sometimes evergreen, and growing all over the planet, the oak is a beautiful, resilient, and important tree to all forest communities. There are 90 species of oak in the United States, 160 in Mexico, and 100 species native to China.
The black oak is native to eastern and central North America and is a large tree of the deciduous variety. It is part of the red oak group (we’ll touch more on that later) and is a very close relative of the hybrid, California black oak (Quercus kelloggii).
Sometimes referred to as the eastern black oak (though it does occur in the center of the continent), it’s scientific name velutina comes from the Latin word for fleece or wooly down. This is in reference to the young foliage and velvet-covered winter buds.
Oak trees are incredibly long-living, and depending on their growing location they can sometimes grow up to 1000 years! This is a rather rare occurrence as their ideal growing conditions don’t occur too often due to forest competition, but they are usually in the old-growth category.
What do Black Oak Trees Look Like?
When black oaks initially start to grow, they put a lot of energy into establishing a sturdy root system to enable a sturdy trunk and canopy. This initially starts as a taproot, which will grow very deep into the soil to access all of those locked in moisture reserves. This is something that oaks have in common with carrots!
Once this is established and the branch growth has begun, the initial taproot will then be surpassed by a more horizontally extensive root system. These will only be an average of 18 inches deep in the soil but will spread sometimes to 7x as wide as the crown of the tree.
Root hairs that grow from the tips of smaller roots absorb the water and minerals within the soil and circulate them throughout the tree. They are also released into the topsoil which helps with the prosperity of forest floor plant life as well.
An interesting feature of oak root systems is their ability to graft together. If oaks of the same genus are growing next to one another, roots are able to grow into one another. This enables trees to share nutrients and water; which is especially helpful if one of the trees is sick or thirsty.
Depending on its growing location, the black oak will be a different height. In northern locations, the tree will grow to be an average of 20-25 meters in height with a trunk diameter of 35 inches. In southern locations they will grow far larger, sometimes exceeding 42 meters in height.
Because black oak seeds are usually dropped in a dense forest canopy, they sometimes reserve their energy for trunk height over branch growth. When growing in a dense forest, branches won’t start to emerge until quite far up the trunk. If growing in an open area, branches will begin their growth very low to the ground.
The crown grows irregularly, and will sometimes look completely different from tree to tree. Although always variable, the lower branches will grow completely horizontally, whereas the upper branches will have an ascending trajectory.
On a young tree, bark will be very smooth in a dark gray shade. Older trees will have started to develop texture in the form of deep furrows and ridges with square-shaped segments with rounded edges that exfoliate away. Mature trees have bark that will be a very dark gray and sometimes black.
The inner bark of the black oak tree is a striking orange-yellow color, with the pigment called “quercitron”. This inner bark was once utilized for its yellow dye in natural pigment dyeing and was widely sold commercially up until the 1940s before artificial coloring was brought to the market.
The leaves of a black oak tree are alternately arranged on the twig, averaging between 4-8 inches in length. Each leaf will contain between 5 and 7 bristle topper lobes that are separated with a U-shaped notch — the width and depth of the U shape is variant on each species of an oak tree.
The top surface of the leaf is a deep, dark green color with a shiny sheen, and the lower surface of the leaf is a dull yellow color with fine hairs that grow in clumps.
Black oak leaves that receive a lot of sun exposure will have deeper notches, and develop very velvety winter buds.
How do Black Oak Trees Reproduce?
Oak trees possess monoecious flowers, meaning that they will often possess both male flowers and female flowers on the same stalk.
Staminate flowers (male sexual characteristics — pollen-producing) will develop from the leaf axils from the previous year. These flowers form as catkins, which are clusters of flowers with either indistinct or no petals.
Pistillate flowers (female sexual characteristics — ovule producing) will develop from the leaf axils of the current year. They will flower around the same time as the new spring leaves do, anywhere from April to May.
Once an oak tree is fertilized through either wind pollination or insect pollination, it will produce fruit in the form of a nut, in this case, an acorn. They form in clusters of 2-5 and are enclosed in a scaly cap. The cap of a black oak covers almost half of the entire nut.
The time of acorn maturation varies depending on the oak subspecies, though they all take quite a while to fully mature. In the case of the black oak, they can take up to 2 years to become fully mature.
Once they reach maturity they are a nice light brown color, and they will usually become mature within the months of August to October two years after their original emergence. The acorns are dispersed through gravity, and also through the defecation of the animals that feed on them.
Not many acorns will actually have the opportunity to successfully germinate because they become destroyed through the digestion process, or because they are left under a dense forest canopy and don’t receive enough light to grow into a sapling.
When growing in forest stands, black oaks will usually start producing their seed crops after about 20 years, with their optimum seed production occurring between the ages of 40 and 75.
Oaks are usually a rather reliable and consistent producer of seeds and will grow a very productive crop every 2-3 years.
However, because acorns are so liked by so many forest-dwelling creatures, much of those productive crops are eaten up before the acorns are able to germinate and grow into new seedlings. In the off years, mostly all of the acorns will be eaten, resulting in no black oak sprouts.
What Are Some Other Types of Oak Tree?
Part of the beech family, Fagaceae, the oak is a very large species and contains around 500 different subspecies. The family contains both deciduous and evergreen varieties, and they grow in cool temperatures, tropical temperatures, and everything in between.
The United States contains 90 of the species, Mexico has 160 native oak species, 109 of those which are endemic (only ever have and only ever will grow there) and China has 100 native tree species.
Because there are so many, they have been divided into two subgenera, and 8 sections within those two subgenera categories. These divisions are classified by the different evolutionary traits of the trees. The two subgenera are identified as the “old word” species that occur in Eurasia, and the “new world” species which occur in the Americas.
Quercus – New World
White Oaks (sect. Quercus)
Native to Europe, Asia, and North America, white oaks are a shorter species with sweet acorns and are deciduous.
Live Oaks (sect. protobalanus)
Native to the southwestern United States and northwestern Mexico, live oaks are a shorter species with bitter acorns and are deciduous.
Southern Live Oaks (sect. virentes)
Native to the southwestern United States, southern live oaks are shorter with fast maturing acorns and are of the evergreen variety.
Short Oaks (sect. ponticae)
Native to the eastern United States, short oaks are obviously a short variety with uniquely shaped leaves and are deciduous.
Red Oaks (sect. lobatae)
Native to central and southern America, red oaks are taller, acorns take longer to mature, and are deciduous.
Cerris – Old World
Ring Cupped Oaks (sect. cyclobalanopsis)
Native to eastern and southeastern Asia, ring cupped oaks have distinct acorns with cups with rings of scales, and they are of the evergreen variety.
Turkey Oaks (sect. cerris)
Native to Europe and Asia, turkey oaks are a taller variety with bitter acorns that take longer to mature, and they are deciduous.
Eurasian oaks (sect. llex)
Native Europe and Asia, Eurasian oaks are medium-sized trees with acorns that take longer to mature, and they are of the evergreen variety.
Where do Black Oak Trees Grow?
Black oaks are a very prosperous and wide-spreading tree, despite all of their damaging agents. Oak forests grow all over eastern and central North America and occur in all of the coastal states, starting from Maine to Texas. They grow as far inland as Oklahoma, Kansas, Nebraska, Minnesota, Michigan, and Ontario in Canada.
They tend to grow their best in rich soil that occurs in coves, or on lower slopes that are south facing, though they will grow on slopes with any aspect. They grow up to elevations of 1200 meters above sea level.
Depending on the local climate, in warmer climates, they will grower in cooler, moist areas, and in colder climates, they will grow in warmer, moist areas. These types of regions usually occur in the USDA growing zones between 3 and 9.
What are the Growing Conditions of Black Oak Trees?
As long as the soil is moist, a black oak will be happy. It grows best in soils that are very well-drained and can be either loamy or silty clay. Usually, the best type of soil will be derived from glacial materials, like limestone, sandstone, or shale.
If a black oak is growing in soil that is on the drier side, that soil should also be slightly more acidic.
Black oaks are considered as being intermediately tolerant to shade, though that does result in their canopies being irregularly and flatly shaped, and with a lesser chance of seed germination.
What are the Damaging Agents for Black Oaks?
Oaks suffer from more than several damaging agents, though remain to be a very prosperous tree considering.
- Wildfire – when subject to wildfire damage, the fire will kill the cambium within the heart of the tree. This creates an opening for fungus species to enter and cause infection.
- Oak Wilt (bretziella fagaceaerum) – oak wilt is a vascular disease that affects the trees’ ability to transport water and nutrients. The tree will die only a few short weeks after initial symptoms occur.
- Sap Feeding Beetles (nitidulidae) – these beetles will burrow through oak roots and travel through root graft connection under the soil, resulting in mass infection through oak stands. Small oak bark beetles are the most prolific of sap-feeding beetles.
- Shoestring Root Root (armillaria mellea) – when a tree has been weakened by either fire, draught, flooding, or lightning strike, insects invade vulnerable areas and increase the area in susceptibility.
- Cankers caused by Strumella Nectaria – though cankers grow and are unsightly, they seldom actually kill the tree. However, these cankers act as open wounds and make the tree vulnerable to fungus infection.
- Foliage Diseases – foliage disease usually affects oaks in the red oak subgenera, and cause infections to the leaves: anthracnose (gnomonia quercina), leaf blister (taphrina spp.), powdery mildew (phyllactinia corolla microsphaera alni), oak pine pits (cronartium spp.), leaf spots (actinopelte dryina).
- Tunnelling Insects – insects attack boles in oak trees and tunnel, which causes the degradation of lumber quality; carpenter worm (prionocstus robiniae), red oak borer (enaphalodes rufulus), towline chestnut borer (agrilus bilineatus), oak timber worm (arrhenodes minutus), columbian timber beetle (corthylus columbianus).
- Defoliators – lepidopteran species (moths and butterflies) that feed too generously on oak foliage, causing damage to photosynthesis capabilities; gypsy moth (Lymantria dispar), oak leaf caterpillar (heterocampa manteo), orange striped oak worm (anisota senatoria), brown tail moth (euproctis chrysorrhoea).
- Acorn Damage – pests that burrow into growing acorns and either eat them entirely or damage them; nut weevil (curculio spp.), gall-forming cynipids (callirhytis spp.), filbert worm (melissopus latiferreanus), acorn moth (valentinia glandulella).
How are Black Oak Trees Used?
The wood of black oak trees is very hard and coarsely grained. This wood commonly be used to make fence posts, railroad ties, and as fuel. However, because of all of the damaging agents mentioned above, black oak wood will have many defects. For this reason, black oak is not a very common type of wood used in the lumber industry.
The inner bark of a black oak tree is a vibrant orange-yellow color, and for many centuries was used to achieve the pigment called “quercitron”. It was widely used until the 1940s until artificial coloring was brought to market. The tree was even nicknamed “yellow oak” because of this use.
The foliage, twigs, and acorns are a very important source of food for several animal species. Specifically, acorns are eaten by many squirrel species, along with deer, wild turkeys, squirrels, and other small rodents.
Is black oak good firewood?
Because black oak wood is very dense and hard, it is a wood that has a high heat capacity and will burn slowly. Though it is not the best option for meat smoking, black oak makes a medium-good option of firewood.
What animals eat black oak acorns?
White-tailed deer, wild turkeys, squirrels, raccoons, chipmunks, and many other animals eat black oak acorns.
What causes the black center in oak trees?
Anthracnose is a disease that starts on the leaves of oak trees and eventually spreads to the branches, then the trunk of the tree. What begins as a leaf spot infection will turn into complete heart rot in the tree, which looks like a black dead center.
What are the black spots on the leaves of my oak tree?
Oak trees are subject to many leaf infections, depending on what the spots look like, it could be from anthracnose, leaf blister, powdery mildew, oak-pine pits, or leaf spots. All of these are separate fungal infections that result in the spotting of oak foliage.
How long do black oaks live?
Oak trees are very long-living trees, and some of them can live to be about 1000 years old if they are in the exact ideal conditions. Black oaks will usually live to be around 200 years old because they are subject to so many diseases and pests.
How fast do black oak trees grow?
When growing in moist soil that is well-drained and loamy, a black oak can grow less than a meter a year. This is considered as being a rather slow-growing tree. When in less than ideal conditions, they will grow less than 12 inches a year.
How tall do black oak trees get?
Black oaks are a medium-sized variety of tree and will grow to be between 20 and 25 meters in height.
What is the difference between black oak and white oak?
The easiest way to differentiate black oak trees and white oak trees is through their leaves. Black oaks will have shiny leaves, and white oaks will have matte leaves. Additionally, the bark of black oaks is a far darker shade of gray, whereas white oaks will have bark that is a lighter shade of gray.
What is the difference between black oak and red oak?
Red oak trees will have leaves with a more shallow U shaped notch than the black oak, and the red oak has larger acorns, smaller buds, and a reddish inner bark instead of yellow inner bark.
Are black oak trees deciduous?
Some varieties of the oak trees are deciduous, and some are evergreen. Oak trees that live in Eurasia are commonly evergreen, whereas oak trees that live in the Americas are deciduous.
Black oaks are a deciduous trees. This means that they drop their leaves seasonally. This happens in the fall in preparation for the coming winter months. Deciduous trees will go dormant in the winter and no longer need to photosynthesize, hence the leaf drop.
This is because there is not enough energy from the sun in the winter to allow for proper growth. When spring arrives, deciduous trees will then grow a new set of spring leaves and come out of dormancy.