The same is also true of box elder (Acer negundo), which is really a maple. In foliage, the box elder is confusing since it displays compound leaves with three to seven serrated leaflets, unlike other maple species that display lobed leaves. Accordingly, box elder resembles an ash instead of a maple. This has resulted in the common name “ash leaf maple.”
In winter, however, box elders become apparent when their two-inch V-shaped winged keys hanging in eight-inch clusters catch the eye even from some distance in open woodlands and along streams. Box elders are dioecious; that is, like holly, the male and female flowering parts appear on separate plants. This technique insures genetic diversity in successive generations. And for this reason, box elder specimens located in winter by their fruiting clusters will be female, but a male generally won’t be too far away.
Like sweetgum, box elder is relatively infrequent in our section of WNC so that these wintertime techniques for locating them can be useful and make a drive more interesting.
Many observers don’t have a high opinion of box elder, calling it “weedy, messy, and short-lived.” One article described them as “maple’s poor relations.” To my way of thinking and seeing, however, a mature tree in an open, fertile situation is a fine sight.
One such female box elder specimen is located here in Bryson City. About 30 feet tall with a rounded head, broadly spreading limbs, and a short near-black trunk, she makes a stately appearance. And she lights up like a Christmas tree on bright days when the numerous fruit clusters reflect the slanting winter sunlight.
Where you locate fruiting box elders you’ll be able to observe a host of winter birds that feed on the readily available seeds. Evening grosbeaks are especially fond of them.
Take a closer look at the fruit clusters and you’ll find that the paired keys are broadly winged. The membranous flanges are an adaptation that enables some tree species to disperse their seeds far from the parent plants, another technique that ensures genetic diversity. The winged “keys” are also called “samara.” They occur on ash, elm, and other types of deciduous trees. Pine seeds also have winged appendages for the same reason.
When the strong winds of March arrive, box elder is ready to set free its winged fruit. In pairs and singly the thousands of seeds on a given tree are lifted high into the air and blown for surprising distances. Those that come to rest on suitable moist soils of open woodlands, stream banks, and fence rows germinate and propagate the species.
Here in the southern mountains, box elder is generally encountered in the lower elevations. But on occasion specimens can be located in the middle elevations up to 3,500 feet where windblown samaras have alighted and found suitable footing.
At whatever elevation, look for them from December into late February when their fruiting clusters shimmer in the winter light.