Question: What can you tell me about the sourwood tree – Oxydendrum arboreum? Karl, Towson, Maryland
Answer: Karl, the sourwood tree – Oxydendrum arboreum – has exceptionally good foliage from spring to fall, beautiful summer flowers and a dense pyramidal form (the maximum height is 60 feet although the tree is usually smaller) make the sorrel or sourwood tree. Oxyclendrum arboreum, one of the most serviceable ornamentals hailing front the Southeast.
The name sourwood comes from the fact that the leaves and twigs taste sour when they are chewed. but they do temporarily assuage thirst. Fortunately, the species is hardy all the way up the eastern coast to Boston, and now is being planted on the Pacific Coast as well. However, it doesn’t do too well under crowded city conditions, and in dense woods it may be little else than a tall, spirally twisted trunk with a few branches at the top. But bring the tree out into the open, where it gets sunlight, and it really comes into its own.
Needs A Background Frame
Evergreens, especially hemlocks, make an excellent background for the showy sourwood, with its lustrous leaves, white summer flowers and scarlet autumn dress. Planted alone as a lawn specimen, it may do all right, but with an evergreen background, even one tree will stand out so beautifully it may easily be the most interesting plant on the place.
The snowy flowers, which are produced in midsummer and last several weeks. are small and bell-shaped. They are similar to the flowers of the blueberry. but are borne in gracefully pendulous racemes 8 to 10 inches long. Usually they are profusely borne – and always at the very ends of the slightly- drooping branches so that the entire tree seems well clothed in flowers in late summer.
A small dried capsule eventually replaces each individual flower. These capsules have ornamental value since they hang on the branches in gracefully drooping clusters all through fall and far into the winter – in fact, until winter winds or ice and snow break them off. Although they are a light brown, certainly not as colorful as the fruits of some trees, they give the tree added interest over a long period.
Beauty of Autumn Color
When the leaves first appear in spring, they unfold a light bronze, then gradually change to a splendid, lustrous green. Since they are about the same pleasing size and shape of the leaves of mountain-laurel and seldom marred by insects or disease, this tree is highly valued as an ornamental for its spring and summer leaf beauty alone. But in fall, when the leaves turn a brilliant scarlet, it is outstanding. We all like to think of our native dogwood as being at the top of the list for beauty of autumn color, but the glossy red leaves of the sourwood boast an even more beautiful shade.
However, the autumn color of the sourwood can he a great disappointment if the tree is planted where it does not receive the direct rays of the afternoon sun in late September and October, when the colors begin to change. This planting note holds for all plants with brilliant autumn coloring, for it is the late western sun in early fall which has much to do with bringing bright fall colors to certain plants. On a tree growing in the open, the fall color will not be nearly as vivid on the tree’s north or cast sides as on the west.
The wood of this tree is hard and of little commercial value, although people who live where the tree is native (from Pennsylvania to Florida) have used the wood for tool handles. Since the flowers appear at a time when there are few other trees in bloom, the bees seek the nectar from these flowers and make an excellent honey from it.
Being a member of the heath family, which includes rhododendrons, azaleas, blueberries and heathers, the sourwood requires acid soil for best growth. This is not too difficult to provide, even in a limestone region, for some acid peatmoss mixed with decayed pine needles or oak leaves and sprinkled with a few handfuls of aluminum sulfate gives just the right reaction. If the soil tends to gradually become alkaline again, additional amounts of aluminum sulfate can be applied from tune to time.
Finally, this tree is not seriously infested with disease or insect pests. Consequently it is another in the list of low-maintenance plants with which small home owners should become familiar.
