Wandering through the woods this time of year, occasionally I’ve come across a small deciduous tree laden with cone-like structures that resemble the hops used to brew beer. This is the American – or Eastern – hophornbeam (Ostrya virginiana). A member of the birch family, hophornbeam grows in the understory in a variety of northeastern hardwood forest types. It is also known as ironwood (as are other tree species with exceptionally hard wood) and leverwood, as it was once used to construct levers.
The understory, where hophornbeam grows, is the layer of vegetation beneath the forest canopy (overstory) and is composed of shrubs, saplings, and small trees that grow in the humid, dappled shade. Although some consider hophornbeam a “weed tree,” the species plays a valuable ecological role. Understory plants, including hophornbeam, create vertical diversity in a forest. Multiple layers of vegetation provide a greater variety of food and microhabitats for insects and other animals, enhancing overall biodiversity. Vegetation layers are especially important for birds, as different species prefer to forage and nest at different heights. The black-throated blue warbler, for instance, often nests in understory shrubs or small trees such as hophornbeam.
Hophornbeam grows as high as 20 to 35 feet, with a diameter of 6 to 15 inches. Its ovate, pointed leaves are sharply-toothed, with soft hairs beneath, and alternate on the tree’s slender branches. The bark is gray-brown and sheds off in scaly vertical strips.
This species is widely distributed, ranging from Nova Scotia to Manitoba, south to eastern Texas, and northern Florida, encompassing most of the eastern United States. It also grows in the mountains of Mexico and Central America. In our region, hophornbeam typically grows in mature hardwood forests, as it does well in dense shade. It prefers rich soils but can tolerate a variety of soil types. Hophornbeam is a minor component of most woodlands, but in a few locations, such as the dry oak-shagbark hickory-hophornbeam forests of the Champlain and Connecticut River valleys, it is one of the dominant species. It also makes an attractive landscape tree and does well in shaded yards.
In spring, the hophornbeam tree flowers at the same time as its leaves emerge. Male and female flowers are borne separately on the same tree. The reddish-brown male flowers are arranged in long, hanging catkins in groups of three. The green female flower catkins are considerably shorter – just over ¼-inch long, compared to ¾-inch to 1 ½-inches long for the males. Pollen is disseminated by the wind. Over the course of the summer, fertilized female flowers develop into fruits containing small nuts. The nutlets are enclosed in inflated sacs clustered in conelike structures, called strobiles, that are reminiscent of hops.
In fall, hophornbeam leaves turn yellow, and the strobiles begin to break up. The buoyant sacs surrounding the nutlets aid in dispersal by the wind. Birds feeding on the nuts also spread the seeds. Dry, brownish-yellow leaves may persist on the tree into winter.
Hophornbeam wood is difficult to work because of its hardness. However, this toughness has made it useful for bows, handles, wedges, mallets, and sled runners. People have used hophornbeam bark and its inner wood to treat toothaches, sore muscles, coughs, and other ailments.
Hophornbeam trees also provide food for wildlife. The pre-formed buds and catkins are important winter foods for ruffed grouse. Wild turkey, ruffed grouse, red and gray squirrels, and some songbirds feed on the nuts. Deer and rabbits browse the twigs and foliage. The bark is a preferred food of beavers.
Watch for this interesting little tree on walks in the woods.
Susan Shea is a naturalist, writer, and conservationist based in Vermont. Illustration by Adelaide Murphy Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation: nhcf.org.
