By Michelle Sutton, City Trees Editor
Photos by Michelle Sutton except where noted
Each fall, members of the Society of Municipal Arborists (SMA) select the next year’s SMA Urban Tree of the Year. For 2022, musclewood (Carpinus carolinana) lifted its weight to the top.
This species is treasured for its bark that looks like sinewy flexed muscles, for the wildlife to which it appeals (and helpfully, the wildlife to which it doesn’t greatly appeal—i.e. rabbits and deer), handsome leaves and fruits, and strong performance in moderately stressful urban situations. It can be grown multi- or single-stem and in an urban setting matures anywhere from 15 to 30 feet (4.6 to 9.1 m) tall and wide.
Musclewood is native to the eastern U.S. and southern parts of Canada, but with its Zone 3 to 9 hardiness, its potential planting range is much wider. Like most trees it prefers a loamy soil, even moisture, mid-range pH, adequate soil volume, freedom from soil compaction, and full sun. “It can tolerate wetter than normal soil and partial shade, though shade tolerance in a mature musclewood tree is unusual,” says Cornell Urban Horticulture Institute Director Dr. Nina Bassuk.
She adds, “Once established, musclewood can tolerate occasional dry periods, but I would not count it as notably drought tolerant.” However, Bassuk notes that within its large native range, there are surely musclewood ecotypes that may yield interesting variants for different site conditions—like persistently dry ones—and for ornamental traits. “There are some new cultivars that have been selected for better fall color—a more vivid orange-red,” she says.
Bassuk puts musclewood in the “moderately difficult to transplant” category. “For this reason, I would recommend transplanting it as a small-caliper tree,” she says. “We experimented with planting it bare root at 1.5-inch (3.8-cm) caliper in Ithaca, New York but had enough losses that I probably wouldn’t recommend bare root for Carpinus caroliniana.”
Providence, Rhode Island City Forester Doug Still says that in his tenure they’ve planted 29 musclewood as street trees in both lawn strips and sidewalk cutouts. “We’re just getting started planting it,” he says. “It can be hard to source, so when I see it become available in nurseries, I buy as many as I can. I like it because it’s another native tree that we can add to our palette. What makes it unique for me are the interesting-looking seeds—papery seed clusters that draw attention for months from summer into fall.”
Still says that there are maintenance considerations, however. “Musclewood requires early structural pruning because of its dense branching pattern,” he says. He says that the tree requires stewardship—weeding, mulch, and most especially, watering—during the establishment period. “I’ve observed that if it gets enough water in those critical first three years, it takes off. Ours are looking great, and musclewood strikes me as a good native plant alternative to many other trees.”
I would like to use musclewood in Alexandria once I can find a good local source. It reminds me of the woods where I played as a child … they were full of musclewood trees. In our city, we have small rights-of-way with lots of overhead obstructions—and this tree seems to be the perfect size for that scenario.
—Darren Green, Landscape Architect, City of Alexandria, Louisiana
Musclewood Quick Facts
- Musclewood is monoecious (male and female flowers—both catkins—borne separately on the same tree). Flowers are wind-pollinated. The fruit type is a nutlet.
- Leaves are alternately arranged, with sharply double-toothed edges. Musclewood provides food for the larvae of the Eastern Tiger Swallowtail and Red-spotted Purple butterflies. Fall color is yellow, orange, or red and not super showy on the straight species—but cultivars offer enhanced color.
- One common name for Carpinus carolinana is blue beech, but the plant is in the birch family (Betulaceae), not the beech family. Another common name is American hornbeam—not to be confused with American hophornbeam (Ostrya virginiana)—because musclewood is said to “take polish” as readily as animal horns.
- Songbirds like yellow-rumped warbler eat the tree’s nutlets as do ruffed grouse, squirrels, turkeys, and foxes. Black-capped and Carolina chickadees nest in cavities of mature musclewood trees, and wood thrushes build nests in the canopy. Deer and rabbits occasionally browse it, but it’s not their preferred snack.
- Musclewood grows slowly and is relatively short-lived, as it typically senesces before reaching 100 years old. Despite its dense wood, when it starts to rot, it tends to decline quickly.
This is one of those trees that should be more poplar than it is here. I had never seen it until the 1990s, when it suddenly but only briefly became poplar as a street tree for new medians in at least one of the towns that I worked for a few years later, as well as various tracts of homes. They were grown and balled and burlapped in Oregon. They became unavailable as quickly as they appeared. I have not seen a new specimen since then. The street trees have worked out well, and are certainly better than some of the street trees that we use, such as London plane (sycamore), crape myrtle and various locusts.
I learned it as ‘hornbeam’. It is not native here, and all that were planted are cultivars.
Must reseed and dropping seeds and pollen bracts, must be a very messy tree.