A tree for all seasons
Male catkins
Leaves showing fall color
Hop-like fruits
Distinctive flaky bark (photos courtesy Katja Schulz via Flickr)
October 2024
by Steve Carroll, Contributing Columnist
Despite having four-season interest, Eastern hophornbeam (Ostrya virginiana) is often underappreciated and underplanted. One distinctive feature — and the source of its most widely used common name — are the distinctive fruit clusters that resemble those of beer-making hops. Another of its common names, ironwood, recognizes its very hard wood, but this name is more often applied to the closely related Carpinus caroliniana (also called musclewood). Yes, common names can be confusing.
Hophornbeam is a slow-growing, medium-sized tree that may reach 30 to 40 feet in height. It’s in the birch family (Betulaceae), so is related to birch, alder and filbert, as well as the ironwood/musclewood mentioned above. It will grow in full sun to full shade, preferring some shade, and it does best in moist to dry soil having a slightly acidic to neutral pH. Hophornbeam tolerates drought, wind and ice, but not flooding or salt. During spongy moth (formerly gypsy moth) outbreaks, it can experience significant leaf loss but otherwise does not suffer greatly from insects or disease.
Because of its wide environmental tolerance and resistance to drought, hophornbeam can be planted as a street tree and in and around parking lots. Especially when grown in the open, lower branches are often horizontal to slightly drooping. Its natural range stretches from Nova Scotia and Manitoba south to Texas and northern Florida. In the southeast U.S., it is more common inland than along the coastal plain.
Leaves are 4 to 8 inches long and 2 to 4 inches wide. They are usually tapered at both ends, are darker above than below, and have doubly toothed margins. The leaves are fed on by caterpillars of a number of butterfly and moth species. Though not one of our showiest fall trees, leaves do turn yellow to orange-brown.
Flowers are grouped in separate male and female catkins that form on the same tree. Pollination by wind occurs as the leaves expand. After fertilization, seeds form in tight clusters of 10-20 inflated pillow-like sacs, forming the hops-resembling clusters shown in the photo. These sacs, each of which contains a single nutlet, are yellow when formed, then turn brown in autumn. It’s not unusual for these to persist through the fall and into winter.
In addition to its characteristic fruit, hophornbeam also forms distinctive, ornamental bark. On mature trees, the reddish-brown bark forms long, narrow, vertical strips attached in the middle but curled out at the ends, lending a shaggy appearance. This bark contributes to the tree’s horticultural value, particularly during winter.
Buds, catkins and seeds are eaten by deer, small mammals, grouse, turkey and other birds; the leaves are host plants for caterpillars of a number of butterfly and moth species. The hard, heavy, durable wood — harder even than oak, ash and persimmon — has been used in making sleigh runners, wagon wheel hubs, tool handles and more. Native Americans pounded wood chips into a powder, a tonic from which was then used to treat fever, skin conditions and indigestion.
Hophornbeam does not show off. Its spring flowers are overshadowed by those of dogwood and redbud. Its fruits, though unique, can’t compete with pawpaw and persimmon. And its fall foliage fades into the background in competition with sugar maple, red maple and black tupelo. Taken together, however, hophornbeam has something to brag about year-round. If only there was room on our small property to plant one.
Steve Carroll is a botanist and ecologist who speaks and writes about trees, gardening and the world of plants. He is the co-author of “Ecology for Gardeners,” published by Timber Press.