The Viburnums are shrubs of woodlands and moist woodland borders. The European Cranberrybush is an introduced tall shrub, reaching to 10 feet in height, with arching multiple stems.
Twigs are a light greenish brown with numerous lenticels and opposite elongated buds. Buds have brown scales.
Bark on older stems becomes light grayish-brown and stays smooth.
The leaves are opposite, simple three lobed and with course teeth and 1 to 6 small stalkless glands near the base of the blade on the grooved reddish-green stalk. The leaves are green during the summer and turn to a yellowish-brown in Autumn. The leaf underside is pale in color with fine white hair on the surface and more-so on the veins. There is a pair of thread-like stipules where the stalk attaches to the stem, but these drop away early. The groove in the leaf stalk is narrow and v-shaped.
The inflorescence consists of flat-topped clusters of stalked flowers (a cyme), each cluster up to 3 to 4 inches wide, formed on the tips of new growth.
The flowers are of two types - an outer ring of flowers that are particularly showy and noticeable. These are sterile, whereas the inner cluster of small flowers are fertile. The corollas are white 5-parted. The outer flowers have corollas with 5 spreading rounded lobes, a small, short green calyx with 5 pointed lobes. The inner flowers are similar in shape but only 1/4 inch wide. These have the reproductive parts of 5 stamens that have white filaments and creamy colored anthers and which are exerted from the corolla. These are spreading and placed alternate to the petals. The pistil and ovary lack a style. HOWEVER, many cultivars of this species are self-sterile and require another plant to be nearby for pollination, otherwise very few fruits will form.
Fruit: After flowering in May the fruit, a 1/4 inch diameter drupe, forms and gradually changes color from green to the deep red of Autumn. The fruit is acidic and does not make a good preserve, unlike the American Cranberrybush.
Habitat: European Cranberrybush will also grow and fruit in a dryer upland partially sunny site. However, it is not considered as desirable as the American Cranberrybush as it has poorer fall color and is susceptible to aphids. These shrubs are found at Eloise Butler in the dappled shade areas of the Upland Garden.
Names: In the never ending quest for specificity, botanists have recently moved the Viburnum genus into the Adoxaceae plant family, which is a small group of 5 genera of shrubs that have opposite leaves, mostly 5-petaled flowers that produce a small drupe. Minnesota authorities have made this change, USDA has not yet. The genus name, Viburnum, covers a large number of shrubs and the name is an old Latin name for one particular member of the genus. The species opulus, is taken directly from the Greek where it referred to a type of maple and was applied here due to the maple-like leaf shape. Botanists have recently added the variety name opulus to the name of this plant when the American Cranberrybush was renamed from the old species V. trilobum to V. opulus var. americanum. The author name for the plant classification, 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: While there are other Viburnums in Minnesota as denoted below, the one closely resembling this species is the native American Cranberrybush, V. opulus var. americanum. The American variety grows in more low moist sites but does hybridize with the European variety. The leaf stipules are larger and the tiny glands on the leaf stalk are usually stalked. The grove on the leaf stalk is wide and flat bottomed. A fairly complete review of both species is found in this Technical Conservation Assessment (pdf) from the USDA Forest Service.
Above: The typical flower cluster of the Viburnum cranberry bushes. The typical three lobed leaf with course teeth resembling a maple leaf.
Below: The spreading branch structure with fruit clusters born on the ends of new growth. In the 2nd photo - typical color and detail of a mature branch (the smaller branch is a vine not part of the cranberry).
Below: Flower development: 1st photo - bud formation; 2nd photo - separating into umbel shape; 3rd photo- fully developed with the inner fertile flowers open.
Below: 1st photo - Forming green fruit in early June, three weeks after flowering, which by early September has turned red - 2nd photo.
Below: 1st photo - At the base of each leaf is a pair of thread-like stipules. 2nd photo - On the grooved leaf stalk at the base of the leaf are from 1 to 6 (2 here) stalkless oil glands. 3rd photo - Shown is the small 5-lobed green calyx of an outer ring flower.
Below: 1st photo - Leaves are in pairs opposite. 2nd photo - The leaf underside is pale in color with fine white hair on the surface and more-so on the veins.
Below: This prior year twig, shown in the Spring, has buds just above the leaf scar. The brown scales are falling away as the new leaves start to expand.
Notes: European Cranberrybush is an introduced European plant, found in the NE quadrant of North America. In Minnesota, the DNR reports it being found in Freeborn, Goodhue, Hennepin, Lesueur, Nicollet, Olmstead, Ramsey, Sibley, Steel, Todd, Wabasha, Winona and Wright Counties. On the Garden's census it was first listed in 1986. Eloise Butler mentions the plant in a 1926 writing entitled Shrubs in the Wild Garden but does not say it is present in the Garden. Martha Crone did not list it on her 1951 census. In North America it is known only the NE quadrant from Iowa eastward to the coast and in Canada in Ontario, Nova Scotia and New Brunswick.
European Cranberrybush is one of six Viburnums found in Minnesota. Four are native - American Cranberrybush (Highbush Cranberry), V. opulus var. americanum; Squashberry, V. edule; Downy Arrowwood, V. rafinesquianum; and Nannyberry, V. lentago. Two are introduced - European Cranberrybush, V. opulus var. opulus, and Wayfaring-tree, V. lantana. Another Viburnum that will grow nicely in Minnesota, but is not native to the area is Southern Arrowwood, V. dentatum.
Pests: Viburnums are subject to damage from the Viburnum Leaf Beetle, Pyrrhalta viburni, a native of Europe, which first was found in North America in 1947. The larvae feed on the leaves. Female beetles hollow out an egg cavity on the twigs to hold their eggs which over-winter and hatch in the spring. Certain species of Viburnum are more susceptible that others to the pest with V. dentatum, V. rafinesquianum, V. nudum, and V. opulus var. americana being most susceptible. These species will succumb to the pest in 2 to 3 years of infestation unless the eggs are destroyed. For just a few plants, cut off twigs with egg cases in late fall after the beetles have died. [Details in this PDF]
Winter Interest: Plants may hold their red fruit many times well into the winter, making a strong contrast with winter grays and whites. Many birds prefer to eat the berries after they have been once frozen and thawed, which reduces the acidic content.
Lore and medicinal use: Like the American Cranberrybush, V. opulus var Americanum, the European species was also known to have medicinal uses, particularly for the treatment of cramps and spasms. Dried bark was used to make a decoction and infusion. The bark is bitter, containing the glucoside Viburnine. Chaucer mentions the berries when he describes plants suitable for your health, however most people today do not consider eating them. See Mrs. Grieve (Ref. #7) for more details on European use and culture.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"