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The Sourwood Tree

A sweet-as-honey summer flower display

August 2023

by Steve Carroll, Contributing Columnist

Photo courtesy of the Plant Image Library via Flickr.

Homeowners, developers and others who plant trees often favor spring-flowering species. And who doesn’t appreciate those redbuds, dogwoods, serviceberries and other early-flowering trees after a long winter? 

But must we then wait for autumn’s colorful display to again appreciate our trees? Fortunately, the answer is no, as several native species — sourwood among them — flower during the summer. 

Sourwood (Oxydendrum arboreum), also called sorrel tree and lily-of-the-valley tree, shows off dramatic sprays of fragrant, quarter-inch white flowers in early to mid-summer. These hang in clusters from the ends of branches, where they are visited and pollinated by bees. After pollination, small tan to gray fruits that contain tiny, two-winged seeds develop. These dry fruits are sometimes held on the tree into the winter. 

Leaves are 4 to 7 inches long, elliptical in shape, finely toothed and sour to the taste — hence the name sourwood. Fall color is early and spectacular, with leaves turning red to scarlet to dark wine. 

As trees go, sourwood is on the small side, often reaching only 30 to 40 feet tall, sometimes taller, and 8 to 12 inches in diameter. To appreciate the tree’s full possibilities, check out the National Champion Sourwood in Amelia County, Va. This specimen measures 74 feet tall with a 47-foot crown spread! (See Virginia Tech’s “Virginia Big Tree Program” website for details.) 

Sourwood’s native range is fairly limited, stretching north from the Gulf Coast to Ohio and southwest Pennsylvania. This corresponds to Hardiness Zones 5-9, though this tree often grows well outside that range. Sourwoods prefer moist, acidic, well-drained soil in full to part sun, and typically grow in the understory and along forest edges. They do not do well in basic or compacted soil or areas prone to flooding. They look particularly striking when grown as specimen trees, 

but also do well in groupings. This species is in the same plant family as rhododendrons and blueberries (the heath family), but it is somewhat unusual: Oxydendrum is what botanists refer to as monotypic — that is, sourwood is the only species classified in this genus. 

Sourwood has limited economic value. It can be burned, and its hard wood was once used for sled runners. As mentioned above, it makes a dramatic specimen tree but can be difficult to find in local nurseries. Without question, this tree is best known and appreciated for the quality of honey produced when honeybees gather nectar exclusively from sourwood flowers. Descriptions of honey’s taste rival those written about fine wine and shade-grown coffee. An online search brings up countless taste tests and ratings of different kinds of honey, and sourwood honey frequently shows up in these “best of” lists. To cite one example, in a taste test conducted by the Asheville Bee Charmer, a specialty store in Asheville, N.C., sourwood honey earned the top spot. It was described on this store’s website as having “a bold buttery sweetness on the front end, and a caramelized aftertaste on the back end.” Another source described sourwood honey as having notes of anise, maple and spice. 

Maybe it’s time to do your own taste test.

Steve Carroll is a botanist and ecologist who speaks and writes about trees, gardening and the world of plants. He is the co-author of “Ecology for Gardeners,” published by Timber Press.