Flower:

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. A plant may produce only the sterile flowers in a large, round cluster.

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 smooth, the lower surface is paler with fine hairs especially along the veins.

Leaf stalks are up to about 1 inch long, smooth or with a few hairs near the blade, and a narrow groove along its length. At the tip where the stalk meets the blade are 2 to 8 small glands, oval-elliptic in shape, concave at the tip with a distinct rim around the edge. 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 reddish then grayish brown. Older bark is gray, 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.

Fruit:

Fruit is a shiny, berry-like drupe, ¼ to 3/8 inch across, turning translucent red at maturity, and containing a single seed.

Notes:

Guelder-rose is the European counterpart to the native American Highbush Cranberry (Viburnum opulus var. americanum a.k.a. Viburnum trilobum), which is widespread in Minnesota. The real distribution of Guelder-rose in the state is uncertain, since it has been widely planted as an ornamental shrub and looks essentially identical to the native. According to Welby Smith's “Trees and Shrubs of Minnesota”, nearly all of the “highbush cranberry” sold as nursery stock in Minnesota is the European species, even those labeled as the native. 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. While Guelder-rose does escape cultivation, it does so into disturbed soils and is not known to be invasive in high-quality habitat in Minnesota. It is, however, becoming more common than the native in some areas of the state, largely due to the native's habitat loss from development and agriculture.