Hands in the Dirt: Bittersweet

Article and photo by Donna Iverson

This time of year, West Michigan's landscape is one of leafless dark tree silhouettes contrasting sharply with the white snow cover under our feet. But here and there are small bursts of color, ......red, yellow, blue, purple and orange winter berries, like holly, viburnum and bittersweet. They jump out at the eye begging to be noticed.

The bittersweet vine blazes with dozens of bright yellow-orange berries on vines that wrap around trees and fences, often at the edge of wood lots or in waste places.

Decorators love bittersweet and use it for fall and winter displays on wreaths, around candles, and hanging from doorway entrances.

But it's name signals a warning. While the berries look sweet and inviting enough to eat, they are not unless you are a bird or a squirrel. In fact, the berries are toxic containing a poison called solanine. It is the same toxin found in green potatoes.  And while all winter berries may look enticing and edible, most are not. Fifty percent of red wild berries are poisonous.

Most of the Bittersweet found in the Midwest is an alien brought over to this country around the time of the Civil War. Since then, it has been referred to as Oriental Bittersweet. And like most plant aliens, it has become invasive killing off trees by strangulation and displacing its cousin, the American Bittersweet.

The reasons for this are many. It produces more berries than the native variety, which birds eat and disperse the seeds over a wide area. Once established, it is difficult to eradicate as its roots run deep and even a small section of root can regenerate. The Michigan State Extension Service gives eradication instructions on its webpage, saying that a professionally-applied herbicide may be required. See https://mnfi.anr.msu.edu/invasive-species/OrientalBittersweetBCP.pdf 

Once again one of my favorite plants turns out to be harmful to pollinators and killing off trees and native plants. Other offenders, in addition to Oriental Bittersweet, include several honeysuckle varieties, autumn olive, multiflora rose, purple loosestrife, burning bush, wisteria, and English Ivy.

Which brings us back to American Bittersweet which is almost extinct. So how can you tell the difference between the two?  If there is a bittersweet vine in your yard, it is most likely the Oriental variety. To be sure, check where the berries grow.  On the Oriental variety, the berries grow evenly spaced along smooth stems. Berries on the American Bittersweet grow in a clump at the end of a thorny branch.

Bottom line:  if it's Oriental Bittersweet in your yard, best get rid of it.  If you want to grow bittersweet, look for the American variety, Latin name Celastrus scandens. Avoid its cousin Celastrus orbiculatus

Garden tip:  Keep the water in your garden bird bath from freezing over by floating a small ball, such as a ping-pong ball, on the surface. The wind will keep the ball moving and the ice at bay.