Cramp bark’s antispasmodic effect on smooth muscle contractions, especially uterine walls, relieves cramping of muscles, also general muscular pain of the back and arthritis. The bark is boiled and simmered in a decoction for at least 20 minutes, or steeped in alcohol to create a tincture.
Most barks are harvested in early spring when the sap is flowing through the bark, before the flowering and leafing of tree or shrub. You either need a great memory for the location of plants you plan to harvest, or to be able to recognize them out of season. Cramp bark can also be harvested in flower, making it a little unusual.
Cramp bark, V. opulus var. americanum
Identifying cramp bark in the wild (or in someone’s ornamental garden):
There are two varieties of cramp bark, European (Viburnum opulus var. opulus),and American (V. opulus var. americana, also known as V. trilobum). Warning! One has more delicious berries than the other. American cramp bark berries taste like cranberries, so much so that it is commonly called American highbush cranberry, even though it is unrelated to true cranberry= lowbush cranberry (a Vaccinium species more closely related to blueberry bushes). American cramp bark berries are tart and plentiful in Vitamin C, and can be added to jams and jellies, or made into a sauce for a meat dish. European cramp bark berries, on the other hand, have a more acrid taste, far less appealing to eat fresh, so if it tastes strong, it’s the European variety. They are often confused or mislabeled in nurseries, but a taste test is one way to tell them apart.
Don’t let phony identification cramp your style! Cramp bark is also hard to tell apart from small maple trees, and historically this led to a lot of shenanigans, mostly attempts to swap maple bark or other viburnums for the valuable cramp bark in order to make a killer profit. Widespread adulteration almost ended cramp bark’s recognition as part of the official US pharmacopeia, and diluted its effectiveness in the eye of the public for many years. Viburnums have opposite leaves, branches and leaf buds, so maples and ashes are the only group you are likely to confuse them with. You wouldn’t be the first!
Viburnums are bushes 3-12 feet tall, with opposite leaves, and cranberry viburnums have lobed leaves with hairy undersides and spiky things (stipules) at the base of the leaf stem (petioles). If there aren’t any stipules, it’s a maple. Acer spicatum has historically been the most commonly mistaken lookalike, and was a common adulterant, knowingly or unknowingly substituted or mixed into true cramp bark by harvesters or middlemen.
Cramp bark viburnums, American and European can be recognized in winter by their bud scales, a skill we cover in my classes on winter bud identification in March. Their buds have one bud scale in winter, which develops into a pair of bud scales that meet at the edges before they leaf out in spring.
You can tell cramp bark apart from maples by the stipules, and from other viburnums by the leaf shape (with three lobes), and you can tell the variety based on the bumps or glands on located on the petiole (the European variety V. opulus var. opulus has concave glands, the American variety V. opulus var. americanum has convex glands). Not sure it’s a viburnum? Follow this excellent guide from Cornell extension.
European cramp bark is best known in Ukraine as kalyna, the most beautiful flower and symbol of the nation and a woman’s beauty, an important icon found in national imagery. Ukraine at least has never forgotten cramp bark’s significant medicinal value.