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The Monday Garden
Asiatic Bittersweet

Issue No. 40 - December 29, 2002
by Sue Sweeney

I hope you’re busy counting the many blessings of the past year. “The Monday Garden” today is about another beautiful but deadly invader, the Oriental, or Asiatic, Bittersweet, Celastrus orbiculatus [also known as Japanese Bittersweet]. Growing along the roadside, here it is strangling its host tree and using the weight of this past week’s snow to help it topple the host tree altogether.
 

Close-up of the berries

 
When I was a child in upstate New York, we treasured the American Bittersweet, Celastrus scandens, a rare and beautiful plant on the local endangered list. Today on the Connecticut shoreline, I pull up a lot of its Asian cousin.
The native plant grows 10’ to 20’ vines and spreads slowly. Its natural range is Ontario to Manitoba, south to North Carolina and New Mexico (Zones 3- 8). It has separate male and female plants and is bee-pollinated. Its berries are munched up by chickadees, blue jays and mockingbirds, to name a few. It is late-winter survival food for many species, including squirrels. (That means that they don’t like it a whole lot but will eat it when they have to.) The berries aren’t fatal to humans but shouldn’t be eaten because they are guaranteed to clean out the alimentary system in short, albeit painful, order.

The invader, a native of Eastern Asia, Korea, China, and Japan, was first imported to North America in the 1860’s. It was a favorite of conservationists as a quick growing ground cover that provided shelter and food for wildlife, protected against soil and dune erosion, had a 95% seed germination rate, made great material for floral arrangements, and had attractive golden-yellow fall foliage. How could you lose? Well, if you wanted an awful lot of the stuff, growing up to 60’ vines, to the exclusion of a more diverse community, you couldn’t. It’s now in 33 states from Connecticut to North Carolina and west to Illinois. Because it’s as salt tolerant as its American cousin, it’s particularly a problem around the Long Island Sound.

The drive to control the Asiatic bittersweet has further endangered the American native because the two plants look so similar. There are three differences: the American has orange seed covers, the Asiatic’s are more yellow; the American flowers and fruits at branch tips, the Asiatic at the joints between the stems and the leaves; and the American has a pointed leaf, the Asiatic’s has a rounded end and tiny blunt teeth along the leaf edge. To make matters worse, there are reports of interbreeding.

If a small bittersweet vine appears in your garden, you can be pretty sure it’s Asiatic. I don’t recommend waiting until it grows up and fruits (and becomes impossible to root out) to make sure it’s not one of the good guys. To control the Asiatic, you have to pull up all (yes, every little bit) of the root and kill the berries by baking them in the sun for weeks in a sealed black plastic bag. Dump the uprooted plant, or a wreath from the store, in the garbage and guess what you get at the dump? More bittersweet! Indeed, discarded floral wreaths have been a major cause of seed dispersal.

From The Monday Garden. Copyright © by Sue Sweeney. Reproduced with permission. 

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