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Mighty Oaks: Trees of beauty, function and diversity

By Katie Jackson

To fully admire a mighty oak, you may need to look up. To fully appreciate the might of oaks, however, just look all around. You’ll see oaks and their many contributions to our lives everywhere.

Oaks are native to the Northern Hemisphere (primarily Asia, North Africa, Europe and the Americas) and are members of the genus Quercus, which includes 500-600 diverse species worldwide. Approximately 90 oak species are native to the U.S., and 40 of those — more than any other state in the nation — are found right here in Alabama. 

The diversity and abundance of Quercus in our state means we have lots of different kinds of oaks for use in our home landscapes, but it also means that our woodlands and other wild landscapes are stronger. That’s because oaks act as keystone species — dominant species in an ecosystem that support other plants and animals sharing their natural community. Keystone species are so important to their ecosystems that removing them will drastically change, perhaps even destroy, natural habitats. 

Oaks are also vital to our species. Like other trees, oaks provide vital functions that support humankind such as turning carbon dioxide into oxygen, filtering and cleaning air and water and holding soils in place. Their strong, beautiful wood is used to construct many of the buildings that shelter us (not to mention boats that move us around, furniture, flooring and so much more) and their bark has medicinal qualities and is also used for inks and dyes. 

In addition to meeting many of our basic needs, oaks also provide us with such luxuries as barrel-aged wines and whiskies, earthy-flavored truffles and even the subtle nuttiness of acorns (yes, we can eat them, though they may require a bit of preparation and some are tastier than others). And for eons, oaks have been a source of something of inestimable value to human society — inspiration, from which has sprung art, literature, mythology, symbolism and many other spiritual and cultural touchstones. 

Of course, oaks can also beautify our landscapes, and the choices are vast. Oaks are segregated into one of two categories, white oaks and red oaks, based on distinct leaf and acorn characteristics. Both categories, however, offer a wide range of options for tree size (towering giants to petite shrubs) and shape (spreading, towering, rounded and more), as well as diverse leaf types (deciduous to evergreen; lance-like, oval, many-lobed, palmate and many other shapes) and acorn characteristics (large to small, pale to dark and bitter to sweet).  

Among these two groups are many long-lived (surviving 200 years or more; the Seven Sisters Oak in Louisiana is believed to be more than 1,000 years old) species but also some with shorter lifespans. Most oaks tolerate a wide range of growing conditions, including droughty conditions once they are established, and oaks typically require only minimal pruning and fertilizer.

Despite all those fine attributes, however, oaks are often snubbed for home and urban landscapes, mainly because they have reputations for being either slow-growing or for overgrowing their space and because their leaves and acorns can make a bit of a mess. But those issues can be overcome if we pick the right oak for the right spot. 

Begin by assessing the site (or sites) where you’d like to plant an oak. Determine how much space you have for the tree to grow (both in height and width) and how close the area is to buildings, driveways, parking areas, patios, utility lines and other structures that may cause problems with tree size and maintenance. Also assess the site’s nutrient, sunlight and moisture characteristics. 

Now take some time to study up on the many oak species that thrive in Alabama and match your needs to their qualities. An abundance of oak tree information, including specific species traits, is available in books and publications both online and in print. (See a sample list of several free resources in the sidebar). Finally, start looking everywhere for and at oaks — in neighbors’ yards, along streets, in public parks and gardens and in the wild. Seeing them at work will help you pick the perfect mighty oak, even if it’s a mighty small one.

Free Oak Resources

Auburn University’s Donald E. Davis Arboretum houses a nationally accredited oak collection featuring 39 of Alabama’s 40 native oaks; open 365 days a year from dawn till dusk; admission is free.   

Field Guide of Native Oak Species of Eastern North America is a U.S. Forest Service publication filled with detailed information and illustrations representing 50 eastern U.S. oak species. 

100 Forest Trees of Alabama is an Alabama Forestry Commission and the Alabama Department of Education publication that includes an extensive list of Alabama trees including at least 20 oaks.  

A Key to Common Trees of Alabama is a brief guide for identifying 66 Alabama trees by their leaf structure and characteristics.

Katie Jackson is a freelance writer and editor based in Opelika, Alabama. Contact her at katielamarjackson@gmail.com.