- American Cranberrybush (Viburnum opulus var. americanum)
- European Cranberrybush (Viburnum opulus var. opulus)
- Mapleleaf Viburnum (Viburnum acerifolium)
- Squashberry (Viburnum edule)
The Peterson Field Guide for Edible Plants says, ‘A European ornamental occasionally escaped from cultivation, V. opulus [Viburnum opulus var. opulus], is almost a double for Highbush-cranberry, but with bitter fruit.” For this reason, it is important to tell the two apart.
The following web page shows how to tell the two apart (using a table and two links for pictures): http://oregonstate.edu/dept/ldplants/vitr.htm. The American Cranberrybush (var. americanum) has a wide and shallow groove on the leaf petiole, small glands on the petiole and hairs only the leaf veins of the underside of the leaf. The European Cranberrybush (var. opulus) has a thin groove on the leaf petiole, larger, disk-shaped glands on the petiole and often has hairs on the underside of the leaf in addition to the leaf vein hairs.
The book, Manual of Vascular Plants of Northeastern United States and Adjacent Canada points out that the glands on the petiole of American Cranberrybush (var. americanum) are stalked, round-topped and mostly higher than wide. The glands of the petiole of European Cranberrybush (var. opulus) are mostly sessile, concave-topped and wider than high. Based on the third set of images from the top where the one on the left is this plant and the one on the right is American Cranberrybush (taken on May 30, 2011), this plant is clearly European Cranberrybush (var. opulus).
