General: Honeysuckle family (Caprifoliaceae). Native shrubs to 4 m high, with upright, spreading, arching branches. Leaves deciduous, opposite, ovate, 5-12 cm long, deeply 3-lobed, coarsely toothed, with 1-6 large glands near the petiole apex, becoming yellow-red or reddish-purple in the fall. Flowers white, in flat-topped clusters 7-10 cm broad, with flowers of two different types, those in the outer ring sterile, showy, with expanded corollas 1-2 cm broad, the inner flowers much smaller, fertile, with yellow anthers. Fruit berry-like (a drupe), globose, bright red, 8-10 mm in diameter; stone single, strongly flattened. The common name alludes to the resemblance in fruit between the highbush cranberry and the cranberry of commerce (Vaccinium macrocarpon).
Variation within the species.
The North American plants have generally been recognized as the same species as the closely similar native of Europe, northern Africa, and northern Asia – V. opulus L. [var. opulus]. Var. opulus is said to differ from the American variety in its filiform-attenuate stipules and petiolar glands mostly short-pedicellate, round-topped to concave, and mostly wider than high. Voss (1996) notes that “variation between vars. opulus and americanum is too great – and too continuous – to make clear distinctions.” Variants have not generally been recognized from within the American segment of the species, but horticultural selections have been made from plants of both continents, primarily for leaf color, fruit color, and growth habit. The best known of these is the cultivated “snowball bush” (V. opulus var. roseum), a form developed from Old World plants, with spherical inflorescences of enlarged, completely sterile flowers (the "snowballs").
The native variety (var. americanum) is known to hybridize with cultivated or escaped ornamental forms of var. opulus. This may result in the gradual degradation or loss of the native genotype.
Distribution: Var. americanum is widely distributed across north-central North America, from Newfoundland, Nova Scotia, New Brunswick, and Quebec to British Columbia, and in the US from Maine to Pennsylvania and West Virginia, northwestward to Washington. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site. The non-native var. opulus is frequently planted and sometimes escapes; it is recorded from Ontario and New Brunswick and various states in the northeastern quarter of the US – Maine to Virginia and West Virginia, westward to Wisconsin, Iowa, and Missouri.