10 Common Types of Oak Trees In California (with Pictures)
California has a unique environment that has attracted millions of people over the decades. It has a warm Mediterranean climate not found anywhere else in the United States. The northern regions are filled with thick, humid forests, while the southern half of the state is hilly and arid. California is home to some of the most fertile land in the United States.
The various climates have produced conditions ripe for unique oak species to develop and thrive. Oaks are some of the most common species of trees found throughout the United States. Each of these trees has adapted to California’s environment. Below, we’ll discuss ten unique types of oak trees that are native to California.
The 10 Types of Oak Trees in California
1. Blue Oak
|Scientific name:||Quercus douglasii|
|Height:||20 – 60 feet|
|Longevity:||175 – 400 years|
Blue oaks are hardy trees that live in open, arid areas of southern California. They are primarily found at elevations ranging from 500 to 2,000 feet on the low hillsides that dominate southern California. These trees can live for an extremely long time, with some trees living over 400 years.
The tallest of blue oaks can reach heights approaching 100 feet, and they are often called mountain oaks by the locals. Blue oaks are one of the most common oaks native to California and are prized in gardens for their ease of care and appearance.
2. Coast Live Oak
|Scientific name:||Quercus agrifolia Nee|
|Height:||20 – 40 feet|
|Longevity:||125 – 250 years|
Coast live oaks are squat trees with thick bark that propagate in the dry valleys of coastal California. Unlike other oak trees, the coast live oak is fire resistant. The thickness of the bark protects the tree even during hot fires.
Coast live oaks can live up to 250 years in ideal conditions. They are also unique in that they are evergreen oaks and are green year-round.
3. Canyon Live Oak
|Scientific name:||Quercus chrysolepis Liebm|
|Height:||60 – 80 feet|
|Longevity:||100 – 300 years|
The canyon oak is the most widely distributed species of oak in California. It is well adapted to California’s elevated geography. Some of the trees have been found at elevations as high as 9,000 feet or more. They use strong roots to cling to the side of steep canyon walls and sharp slopes on the northern sides of mountain ranges.
The live oak’s strong roots, thick bark, and longevity make them perfect inhabitants of remote canyons. The tree can be found throughout the state, from the northern border to the southern hills. The leaves are simple ovoid leaves that are light green.
4. Interior Live Oak
|Scientific name:||Quercus wislizeni A. DC.|
|Height:||30 – 75 feet|
|Longevity:||150 – 200 years|
Interior oaks are found throughout California at higher elevations. They inhabit dry valleys in the south and low fertile foothills in northern California. Their prevalence in the Sierra Nevada mountains has given them the nickname Sierra Nevada oaks.
Unlike other live oak species, the interior live oak is not very fire-resistant. They quickly die in fires but can remarkably resprout in the aftermath of such events. Despite their vulnerability to fire and relatively narrow diameter (only 1 to 3 feet), interior oaks can still live upwards of 200 years.
5. Valley Oak
|Scientific name:||Quercus lobata Nee|
|Height:||40 – 120 feet|
|Longevity:||150 – 250 years|
Valley oaks are lowland trees that grow at elevations near sea level along the coast and just inland. They are extremely large oak trees that dominate the areas in which they grow. The oldest of these trees can be found with trunks over 5 feet in diameter.
The largest and oldest valley oaks can reach heights of 150 feet and diameters of 8 feet, making them one of the largest species of tree in California. Large clusters of valley oaks live in the Bay Area and central California.
6. Engelmann Oak
|Scientific name:||Quercus engelmannii Greene|
|Height:||20 – 50 feet|
|Longevity:||100 – 200 years|
Engelmann oaks live alongside coastal live oaks in southern California. Unlike live oaks, Engelmann oaks are not evergreen trees, but they can sometimes retain large amounts of foliage through the winter. Engelmann oaks are not particularly tall, and to the untrained eye, they resemble live oaks.
They are sometimes called mesa oaks and are exceedingly rare. They are mostly found on the western edges of California’s great deserts. Engelmann oaks are very tolerant to dry heat and extremely hot fires, allowing them to persist in harsh climates.
7. California Black Oak
|Scientific name:||Quercus kelloggii Newb.|
|Height:||60 – 90 feet|
|Longevity:||100 – 200+ years|
California black oaks are named to distinguish them from their more common cousins. They thrive at elevations spanning between 2,000 and 6,000 feet and grow in hardwood forests found in the mountainous foothills around California.
Healthy black oaks can grow as tall as 90 feet or more and have trunk diameters reaching 4 feet. These giant trees can also live for an extremely long time. There are isolated reports of some California black oaks living as old as 500 years old or older.
8. Oregon White Oak
|Scientific name:||Quercus garryana Dougl|
|Height:||50 – 80 feet|
|Longevity:||100 – 200 years|
Oregon white oaks are large trees found in mixed evergreen forests. They can grow up to 80 feet tall with trunk diameters exceeding 5 feet. They are similar in appearance to valley oaks but are distinguished by their acorn shape and size.
These trees can live up to 200 years in good conditions and have a wide distribution. They can be found in the humid coastal regions of Oregon and Washington through the hot dry areas of northern California. They have deep green leaves with a good shine and can withstand low-intensity fires that spread through their habitat seasonally.
9. Island Oak
|Scientific name:||Quercus tomentella|
|Height:||40 – 65 feet|
The island oak is a unique species of oak tree native to a group of small islands off the coast of Southern California. Island oaks are sometimes called channel oaks due to their location on the California Channel Islands. There is evidence that the oaks were widespread throughout the state in the distant past, but today, they are only found on the islands.
Their rarity and small geographic habitat have landed them on the list of rare and endangered plants kept by the California Native Plant Society. These short squat oaks are usually found clinging to foggy northern slopes of the island’s hills.
10. Shreve’s Oak
|Scientific name:||Quercus parvula var. shrevei|
|Height:||60 – 90 feet|
Shreve’s oak is similar in appearance and habitat to coast live oaks. In fact, many people confuse Shreve’s oaks with coastal live oaks, which are more common. They also inhabit the same foggy coastal valleys that coast live oaks do.
Shreve’s oak only has 350 documented sightings, according to CalFlora, compared to 5,100 documented sightings of coast live oak. The Shreve’s oak wasn’t designated as its own separate species until 1980. Before that, it was considered the same as other coastal live oaks in California.
Most Common North American Oak Trees
These ten oak trees are native to California, but they are not very common throughout the rest of North America. California’s unique Mediterranean climate supports species that thrive on the West Coast but do not grow elsewhere. However, oak trees are prevalent throughout the United States and North America.
Black oaks, bur oaks, laurel oaks, water oaks, live oaks, and pin oaks grow in the 48 lower states from Maine to Baja California. Each climate has unique species of oaks that are slightly different from one another and are adapted to different areas. Live oaks in Florida, for example, are not the same as live oaks in California, though they will bear a passing resemblance to each other.
These ten species make up the group of oak trees native to California. From hardy live oaks to tall red and white oaks, the trees grow on tall, wet slopes to low, arid desert regions. The oak is one of the most common trees in North America and California. Next time you find yourself outdoors on the West Coast, keep your eyes peeled for these unique species of oaks that inhabit the Golden State.
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Featured Image Credit: Andrew Sabai, Shutterstock