When walking through the woods in Appalachia, one may observe some of the understory trees. One of those understory tree species is the Sourwood (Oxydendrum arboreum [L.] A. P. De Candolle).
Sourwood is a member of the Order Ericales, the Family Ericaceae, the Subfamily Vaccinioideae, and the Tribe Oxydendreae. Sourwood is the only member of this genus.
The generic name, Oxydendrum, is Greek for “sour tree” because of the sour-tasting leaves. Oxys is “sharp” or “sour” and dendron is “tree”. The specific epithet, arboreum, is Latin for “tree form” or “tree-like”.
Previous scientific names for this tree were Andromeda arborea L. and Lyonia arborea D. Don. Other common names for this tree are Arrowwood, Elk Tree, Elk Wood, Lily-of-the-Valley Tree, Sorrel Gum, Sorrel Tree, Sorrelwood, Sourgum, Sourgum Tree, and Sour Leaf
Sourwood is both sun- and shade-tolerant. It is a slow-growing and a short-lived tree.
DESCRIPTION OF THE SOURWOOD
Height: Its height is 20-80 feet.
Diameter: Its trunk diameter is 8-24 inches.
Trunk: Its trunk is slender and may lean or divide.
Crown: Its crown is narrow, oblong, rounded, conical, and pyramidal. Its branches are crooked or spreading. The branches may be drooping or upright.
Twigs: Its twigs are slender or stout; hairless; zigzag; and may be yellow-green, gray, or red-brown. They have dark lenticels. Its pith is white and continuous. White-tailed Deer (Odocoileus virginianus Zimmermann) eat these twigs.
Its leaf scars are alternate and are semi-circular or are shield-shaped. They each have 1 C-shaped bundle scar.
Buds: Its lateral buds are alternate, globular, and about 1/8 inches wide. It has 3-6 red-brown, imbricated scales. They are partially embedded in the bark. There are no end buds.
Leaves: Its leaves are simple, alternate, and deciduous. Each leaf is elliptical, lanceolate, or ovate. It is about 3-8½ inches long, about 1-3½ inches wide, and is shiny dark green above and paler below. Its tip is tapered and its base is narrow. It has a leathery texture. The leaf margin is finely toothed. Its petioles are about ½-1 inch long and narrow. There are no stipules. These leaves turn orange, crimson or scarlet red, maroon, or purple in the fall. They may persist for 6 weeks. White-tailed Deer eat these leaves.
Flowers: Its flowers are arranged in 4-10 inch long, slender, 1-sided, drooping, racemous, and panicled clusters at the end of the twigs. Each cluster has about 15-50 flowers. Each flower is about ¼-1/3 inches long, creamy white with a pinkish tinge, and is cup- or urn-shaped. It is radially symmetrical with a 5-lobed calyx, a 5-lobed corolla, 10 stamens, and 1 pistil with a simple stigma and 1 columnar style. All flowering parts are attached below the ovary. Flowering season is May to August. They are insect-pollinated. These flowers are fragrant.
Fruit: Its fruits are arranged in 4-8 inch long clusters. Each fruit is an erect; ¼-½ inch long; ovate, conical or pyramidal; 5-angled; slightly ribbed; and dry capsule. These capsules are yellow-green when young and are silvery gray when mature. Fruiting season is September to October. These capsules persist until winter. These fruits are eaten by Songbirds (Suborder Passeri) and by Mice (Genus Mus).
It splits open along 5 valves to release its 25-100 seeds. Each seed is light brown, pointed, about 1/8 inches long, and has 2 wings.
Bark: Its bark is silvery gray to dark reddish brown, thick, and longitudinally furrowed with narrow, scaly, interlacing ridges that may be horizontally divided into blocks. Its inner bark is orange-red.
Wood: Its wood is hard, heavy, compact, close-grained, and diffuse-porous. Its heartwood is red-brown and its sapwood is thicker and paler.
Habitat: Its habitat consists of moist, rich woods and forest understories. It thrives on acidic soils and cannot tolerate alkaline soils. It may be found upon ridges or within ravines.
Range: Its range covers much of the southeastern U.S, mostly in the Appalachian region and in some adjacent areas.
Uses of the Sourwood:
Sourwood has some medicinal uses. An infusion was used as a sedative and for treating intestinal disorders. The bark was chewed for mouth ulcers. The bark ooze was used for skin itches. The sour sap was used for treating fevers. A leaf and bark poultice was used for swelling. A leaf tonic was made for stomach disorders and for treating fevers, asthma, and tuberculosis.
Sourwood had some edibles uses, too. The sour leaves were chewed to relive thirst. The young leaves were used in salads. The flowers were made into jelly. The flower nectar was made into a very sweet white or amber honey.
The wood has no commercial value and had limited uses. It was used as runners for sleds and sleighs, tool handles, spoons, combs, arrow shafts, butter paddles, pipe stems, turnery, paneling, pulpwood, and fuel. This wood does take a high polish.
Because of its attractive flowers and its colorful autumn foliage, it was planted as an ornamental tree. It was first cultivated in 1747.
A few Native American legends mention Sourwood. Most of these stories are from the Cherokee tribe.
There is an Appalachian folk song called Sourwood Mountain. Although the lyrics often vary, it begins with Chickens a-crowing on Sourwood Mountain.
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