Blackjack Oak: One Tough Tree

Knowing how to identify some key plant species can make a hike or a walk that much more interesting. Next time you're out and about in the pinelands, keep an eye out for the Blackjack Oak, a common sight in our local forests. 

What it is: The Blackjack Oak, Quercus marilandica, is a scrubby deciduous tree that thrives in sandy, acid, well-drained, nutrient-poor soils – so even though it’s not a pine, it’s a perfect example of a Pine Barrens species.

Our pinelands are inhospitable places for plants to grow precisely because of the above reasons, but Blackjack Oaks are abundant here.

The oak genus includes some very stately trees, but Blackjack Oaks aren’t really attractive at first glance. They and other species like them are called scrub oaks for a reason – they’re low-growing, with a shrubby habit, and often have gnarled trunks and twisted branches.

Blackjack Oak leaves are thick and covered with a shiny, waxy substance called cutin that helps keep them from losing moisture, as the tree typically grows in high-sun areas. Compare the feel of a Blackjack leaf to another oak, and you’ll immediately get a sense of how much tougher the Blackjack’s are.

The leaf shape is distinctive, too. Most oaks have lobes around the entire leaf perimeter, but Blackjack leaves tend to have a more triangular shape, with a few fat lobes at the end opposite the stem. It’s this blunt shape that allegedly gave the tree its common name; somebody once apparently decided the leaves look like the handheld weapon known as a blackjack, which is similar to a billy club.

Like a lot of poor-soil plants, the Blackjack Oak is a slow grower, so the tree’s trunk is usually not nearly as big around as individuals of other species at the same age – a skinny looking Instead of putting its energy into great leaps in its height and girth, it develops very tough, dense wood.

That’s a handy adaptation in an environment like the Pine Barrens, where frequent fires are part of the ecological landscape. Like its pinelands neighbor, the Pitch Pine, the Blackjack Oak can survive fire after fire, its important tissues protected by thick, gray, pebbly bark.

Where to find it: Blackjack Oaks are one of the New Jersey Pine Barrens’ most abundant tree species.

A great place to see it growing among many other oak species is along the southern end of the Barnegat Branch Trail, between Barnegat and Waretown. Many head-height Blackjack Oaks grow trailside, and their small size and accessibility make them easy study subjects.

But you’ll see them just about everywhere in our pine forests – you can’t walk even a few feet down most pinelands sand roads or trails without spotting one.

The tree grows in similar conditions in much of the American southeast, including Florida’s uplands and the drier, harsher slopes of the Appalachians.

Why bother: As one of the defining trees of our fascinating Pine Barrens, the Blackjack Oak is a key New Jersey species. When it comes to oaks, it’s something of an odd sibling – unusually shaped in both leaf and stature. But it’s a great example of a niche species that thrives in a tough environment.

As a result, knowing how to identify it can also help you understand the land a little better. If you find yourself in a stand of almost exclusively Blackjack Oak, you can bet the soil under your feet is sandy, acid and poor – terrible conditions for most plants, but no problem for the tough Blackjack.