Friends often ask me to identify mystery plants and those identification attempts sometimes lead me on voyages of discovery. Not long ago I took one of those trips.
My friend asked me to look at a mystery tree growing only about two blocks from my house. I had only a few available minutes, but I decided to take a stab at it. It was already late fall and the tree had no leaves, so I had to go base my opinion on growth habit, overall appearance, bark characteristics and knowledge of the local tree population. Because the tree in question was growing on private property, I couldn’t cheat and refer to the town’s census of street side trees. It was quite a challenge.
Still, there were clues. The tree was a medium size specimen, growing about halfway up a large, sloping suburban lot. It was probably about twenty feet tall, with a trunk that had a definite curve or leaning habit. The most interesting feature of the leafless tree was its appearance from the street. What I presumed to be the drooping remnants of the foliage looked almost fern-like to me. I supposed that the tree might be some kind of locust, perhaps black locus or Robinia pseudoacacia. Black locusts sprout long, drooping panicles of fragrant flowers in the spring and it didn’t seem illogical to think that the remnants of those panicles might remain. I didn’t really have time to delve further and compare the unknown tree to the few black locusts I knew of in a neighboring town.
Reader, I was wrong. The same friend who pointed me towards the tree in the first place found an arborist who was able to make the correct identification. The mystery tree was sourwood—Oxydendrum arboretum.
Sourwood is a native American tree, originally at home in the Allegheny mountains, but now cultivated over a much wider range. It belongs to the same Ericaceae family as low-growing heather, as well as rhododendrons and blueberries. Its closest relations, in fact, are members of the Pieris family, including the common andromeda or Pieris japonica. All ericaceous plants prefer soil on the acid end of the pH scale, which is a fact of life in my part of the world.
“What’s in a name?” asks Shakespeare’s Juliet. In the case of sourwood, quite a lot. Both the common and Latin names describe the same plant traits. The Greek word “oxys” means “sour” and “dendron” means “tree”. “Sourwood” is almost a literal translation, but in the case of the tree, it is just a bit misleading. If you were to gnaw on the hard wood, it would not taste sour. If you were to chomp on a leaf instead, you might pucker up. Some of the plant’s common names, including sorrel tree, sour gum and sorrel gum allude to this fact. Sorrel, the herb, is noted for its sour taste. Someone must have noticed a similarity.
Other common names also have a tale to tell and it is a bit more pleasant. Sourwood is sometimes known as “lily-of-the-valley tree” and “tree andromeda”. The names come from the tassel-like panicles of tiny, bell-shaped flowers that appear any time between June and August. Similar little bells sprout on blueberries and andromeda in the spring, not to mention the heathers that bloom at this time of the year.
The flowers are beautiful to the human eye, but even more attractive to honey bees, who patronize the little bells in droves. Once back at the hives, the bees produce sourwood honey, a clear amber delicacy that is prized by honey connoisseurs.
In the midst of all that activity are the shiny green leaves, shaped like elongated ovals and somewhat reminiscent of those found on peach trees. After all the drama of the flowers and bees is over, the foliage takes on an array of brilliant orange, gold and near-purple fall hues, making sourwood a three-season beauty. The combination of desirable traits adds up to a tree that Dr. Michael Dirr, Professor Emeritus at the University of Georgia and author of the Manual of Woody Landscape Plants, characterizes as one of his favorites.
The tree is even eye-catching when leafless. The long tassels that held the flowers persist, bearing capsules filled with narrow seeds. It was those long tassels that drew my friend’s eye and, indirectly, began my sourwood journey.
Sourwood is not hard to grow if its requirements are met, including well-drained, acid soil and full sun or light shade. The trees are native woodland-edge vegetation, so they can live harmoniously in proximity to larger trees, as long as the shade is not too intense. They are probably best used as specimen, rather than street trees, as they, like many suburbanites, are sensitive to the disturbances caused by heavy street traffic. Still, the tree’s relatively small size makes it perfect for other locations on suburban or rural lots. Sourwood is relatively pest-free, so it surprises me that it is not more widely grown. If you have the right conditions and want to start a new fashion in your neighborhood, try ForestFarm, 14643 Watergap Rd, Williams, OR 97544; (541) 846-7269; www.forestfarm.com. Free catalog.