A number of species of Erica (heath) are cultivated, though few are hardy this far north, and none are known to be escaped here. They would key to the couplet separating Empetrum and Calluna, which they resemble in 4-merous flowers and tiny linear leaves, but the latter are mostly whorled and not auriculate; the sepals are shorter than the petals.
All species found in Calluna
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. April 28, 2017. http://michiganflora.net/genus.aspx?id=Calluna.