Viburnum opulus var. americanum (American Highbush Cranberry)
|Also known as:|
|Life cycle:||perennial woody|
|Habitat:||part shade, sun; moist soil; forest edges, clearings, swamps, fens, shores, banks|
|Bloom season:||May - June|
|Plant height:||8 to 15 feet|
|Wetland Indicator Status:||GP: FAC MW: FAC NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Flat clusters 2 to 5 inches across from new lateral branchlets of one-year old branches, emerging after the leaves. Flowers are 5-petaled and have 2 forms: around the edge of the cluster is a ring of 5 to 12, showy, bright white flowers up to 1 inch across; in the center of the cluster are dozens of creamy white, 1/8 to ¼-inch flowers. The large flowers are sterile, lacking stamens or pistils, and the small flowers are fertile, with 5 long, pale stamens.
Leaves and bark:
Leaves are simple and opposite, the blade up to 4½ inches long and nearly as wide, slightly rounded to straight across at the base, with 3 lobes each tapering to a pointed tip and can resemble a maple leaf. Edges are coarsely and irregularly toothed to toothless or nearly so. Upper surface is dark green and usually sparsely hairy though may become smooth; the lower surface is paler with fine hairs especially along the veins.
Leaf stalks are about 1 inch long, smooth or with a few hairs near the blade, and a shallow groove along its length. At the tip where the stalk meets the blade are 2 to 4 small glands, round to oval in cross-section, flat to convex at the tip. At the base of the leaf stalk is a pair of thread-like appendages (stipules) up to ¼ inch long.
New twigs are mostly hairless, green to reddish with raised lenticels (pores), turning tan to grayish brown. Older bark is gray to gray-brown, thin, and smooth to slightly rough. Main stems are up to about 2 inches diameter, typically multiple from base, sometimes arching and rooting where the tip touches the ground, sometimes root suckering.
American Highbush Cranberry, also known as Viburnum trilobum, is a common shrub of moist soils in about 3/4s of Minnesota. It is nearly identical to Guelder-rose (Viburnum opulus var. opulus), an introduction from Europe that's been widely planted as an ornamental and escapes cultivation. The easiest way to distinguish the two is to look at the glands at the tip of the leaf stalk near the blade (magnification is helpful): those of Guelder-rose are typically shorter than wide, oval-elliptic, and bowl or cup shaped (concave) with a distinct rim; those of the native are typically taller than wide, round to oval, flat or rounded (convex) at the tip, and lack a distinct rim. The groove in the leaf stalk is said to be narrow and deeper (more or less V-shaped) in Guelder-rose where the native has a broader, flat-bottomed groove, but this can be variable and is not diagnostic by itself. The native is more likely to have sparse hairs on the upper leaf surface but this is also variable. The two apparently do hybridize, which makes it even more challenging.
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- American Highbush Cranberry plant
- American Highbush Cranberry habitat
- leaves can be toothy or not
- pale leaf underside
- flowering branches
Photos courtesy Peter M. Dziuk taken in Clearwater, Cook, Itasca, Lake, Otter Tail, and Washington counties.
Have you seen this plant in Minnesota, or have any other comments about it?