Illustration by Adelaide Tyrol
Also called sweet birch, cherry birch, or mahogany birch, this species is perhaps the only tree around that is best recognized by the flavor of its twigs. The inner bark, as any twig-chewing child can tell you, is delicious and fragrant: its wintergreen taste is from the very same oil found in Gaultheria procumbens, a small, creeping forest plant also called wintergreen.
So many black birch saplings were once chipped and distilled to make oil of wintergreen that for a time, the tree became rather scarce. Though they were being phased out, a few wood-fired stills continued to operate into the 1950s, a while after it was discovered that oil of wintergreen could be made synthetically from wood alcohol and salicylic acid – without using either black birch or wintergreen.
Since that time, black birch has rebounded and coincidentally has benefited from several other trees’ misfortunes. It is one of the species that has replaced American chestnut where chestnut once was a major component of the forest, and oak stands killed by gypsy moths now have more black birch. In recent years, black birch has filled in where hemlock woolly adelgid, a deadly non-native insect, has taken out the hemlock.
Yet another reason that we may see more black birch in the future is that, perhaps because it leafs out early in spring – earlier than ferns – black birch is one of the best tree species at growing though the dense fern layers that sometimes keep trees from regenerating. And then there is climate change. Now black birch grows best in the southern Appalachians, but perhaps soon it will be happier throughout the Northeast. At present, it is uncommon in northern New England and northern New York state.
Black birch is a lovely tree and produces beautiful wood that darkens with age, so no reason to begrudge its recent or anticipated successes. The bark resembles that of black cherry: lustrous, smooth, and dark red on young trees, and black, with loose, curled, scaly black plates on old trees. Although it prefers a nice place to live – moist, deep, slightly acid, well-drained soils – it is also found on rocky, drier sites, where large specimens often have tortuous trunks and branches. These rock-bound trees do not make good sawlogs, but they add great interest to the landscape. In a fertile forest, the tree grows straight and tall, typically to 60 feet and up to two feet in diameter, with a long bole free of branches.
Before there were dry kilns that make it possible to tailor a drying schedule to suit different species, black birch had a bad reputation for its insistence on warping, but now this trait has been conquered, and sometimes it is just mixed in with yellow birch at the sawmill. Once dry, it is stable and holds its shape. It glues well, can be turned on a lathe, and is used for veneer, as well as for furniture, paneling, and flooring.
Although black birch bark looks a lot like black cherry, both when young and old, its three- to four-inch ovate leaves are wider, with more prominent veins. In flower and fruit, black birch is clearly a birch. Like yellow birch and paper birch, drooping male catkins are in place and obvious all winter. Seeds in the erect female cones mature in autumn and drop to the ground through the winter. The tiny seeds can be blown long distances across snow and are eaten by small birds. The buds, twigs, and catkins provide food for grouse, deer, hare, and squirrels.
Native Americans used the leaves and bark to treat a variety of ailments, but the best known non-timber product from black birch is birch beer. Donald Culross Peattie, in his 1940s book, A Natural History of Trees in Eastern and Central North America, describes the process: “Tap the tree as the Sugar Maple is tapped, in spring when the sap is rising and the buds are just swelling; jug the sap and throw in a handful of shelled corn, and natural fermentation – so the mountaineers tell us – will finish the job for you.”