Facts About the Sourwood Tree

Contrasts define the Sourwood (Oxydendrum arboreum), a small- to medium-sized native North American tree. It has sour leaves and sweet-nectared flowers. Its dark-green summer foliage is replaced with brilliant red flowers. Because gardeners prize its fall beauty, the tree is often taken from the wild, but it is difficult to transplant or grow from cuttings. Sourwood is slow growing and short lived. It has a narrow, oval or pyramid shape with branches that droop at the ends. It grows from 20 to 55 feet tall, with an average diameter of 14 to 16 inches.

Family

Sourwood is the only member of its genus. There are no known subspecies, varieties or forms, but there are two known cultivars, "Chameleoni" and "Mt. Charm." Sourwood is also called the sorrel tree, lily-of-the-valley tree, titi tree, arrowwood, sorrel gum, elk tree and sour gum. Its genus name, Oxydendrum, is derived from the Greek word for a "sour tree," because its foliage tastes bitter due to the oxalic acid in the tissues o the leaves.

Sourwood belongs to the Ericaceae (heath) family. It is related to azaleas, heather, huckleberry, cranberries, blueberries, laurel, rhododendrons and manzanita.

Locations

Sourwood grows in the eastern and southeastern United States, in USDA hardiness zones 5 through 9A. It ranges from Illinois to Florida, though it has also been found in Texas.

Sourwood ranges from the southern tip of Illinois to the gulf coast in Louisiana to Florida. The tree is listed as threatened in Indiana and endangered in Maryland.

Preferences

Sourwood grows best in moist, well-drained acidic soil with a pH range of 3.7 to 6.5.

While sourwood can survive a dry location once it has been established, it is very sensitive to drought and intense heat. It prefers full to partial sun.

Wood

Although its leaves are sour, its wood is not. The wood, which has no taste or odor, is hard, dense and close-grained. Its heartwood, which is difficult to find among all the sapwood, is light gray with a hint of brown and red. Sourwood's wood has been used for tool handles, sliding bearings for wheels, machine parts, butter paddles, arrow shafts, sled runners and fuel.

Food and Medicinal Use

Sourwood's amber-colored sap is often collected and evaporated into syrup. The sap's residue, called sourgum, can be chewed.

Native Americans would infuse sourwood leaves to treat menstrual problems, diarhhea, lung problems and nerves. They would chew the sap or gum for mouth sores, and apply the sap or inner bark to irritated skin.

Early settlers used sourwood tinctures to treat urinary problems, diarrhea, dysentery and fever.

Because there are many poisonous plants that resemble sourwood, you should use this information only for educational -- not medicinal -- purposes.

References

• Urban Forestry South: Sourwood Tree
• Forest Service: Sourwood Tree
• University of Arkansas: Sourwood Tree

Resources

• USDA Hardiness Zones