There are roughly 400 species of oak trees from the genus Quercus, including those oaks commonly referred to as live oaks. Live oaks are oak trees that are evergreen, whereas other trees from the genus Quercus lose their leaves annually. In Southern California’s coastal canyons, three species of evergreen oak trees can easily be observed. These species are
- the coast live oak or California live oak (Q. agrifolia)
- the canyon live oak (Q. chrysolepis)
- the Engelmann oak (Q. engelmannii)
For an enjoyable hike where all three species may be seen, the hiker might consider hiking the Laurel Canyon Trail in Orange County’s Laguna Coast Wilderness Park.
In addition to the three species listed above, it is common to see hybridized oak trees, such as the Torrey scrub oak or the Torrey hybrid oak (Q. Xacutidens). These hybrid oaks can greatly complicate identification of any given oak tree down to the species level.
Coast Live Oak
The coast live oak (Q. agrifolia), sometimes called the California live oak, is a California native tree confined to Western North America. The coast live oak is considered a red oak, and while it commonly grows between 20 to 40 feet in height, this species can reach as much as 80 feet. Like most oaks, the coast live oak is a long-lived tree, and may reach an age of more than 200 years.
Q. agrifolia var. agrifolia is a variation of the coast live oak. Another variation is the so-called southern coast live oak or the coastal live oak (Q. agrifolia var. oxyadenia).
Canyon Live Oak
The canyon live oak (Q. chrysolepis) is sometimes referred to as the gold cup (or goldcup) oak, the maul oak, the white live oak, or simply the canyon oak. It is a California native, and it is relatively common throughout coastal canyons. In fact, the canyon live oak is the most widely distributed oak tree in California. Generally reaching a height of between 60 and 80 feet, the canyon live oak can live up to 300 years.
Q. chrysolepis var. nana is a recognized variation of the canyon live oak and is commonly referred to as a canyon live oak.
Engelmann Oak
The Engelmann oak (Q. engelmannii), sometimes called the mesa oak or the Pasadena oak, is a white oak. While it is technically a deciduous tree, it frequently retains its leaves year-round, except during hot, dry summers when it is drought-deciduous. Commonly growing to a height of between 20 and 50 feet, it is the rarest of the three oaks discussed here.
Included in the California Native Plant Society’s list of rare and endangered plants, the Engelmann oak is categorized as a “plant of limited distribution.” Despite this listing, the vulnerability of the species to extinction is relatively low. “While we cannot call these plants ‘rare’ from a statewide perspective,” states the California Native Plant Society, “[Engelmann oak trees] are uncommon enough that their status should be monitored regularly.”
Oaks and Southern California Wildfire
Oak trees, such as the three species discussed here are beautiful, but they are also very important in areas with wildfire danger. The broad canopies of oak trees provide shade that keeps the ground below the tree free of invasive, fast-growing and highly flammable flora. In addition, the tree itself is not very flammable, meaning that a fast-moving wildfire will rarely kill an oak tree. Laurel Canyon, the hike suggested at the beginning of this article, burned in the Laguna Beach fires of 1993, for example, and yet the oak forest is still dense and beautiful.
Ret Talbot - Ret Talbot joined Suite 101 in December 2007, and he is now the feature writer for saltwater fish—a topic in which he is both ...
