Holiday décor – a bittersweet invasion

By Mary Van Vleck | Contributor

Editor’s note: After a short hiatus, we are happy to welcome Conservation Currents back to The News. The column is written by members of the Charlotte Conservation Commission, working to educate and build interest in conservation issues affecting our town and the surrounding area. If you have a specific question you’d like them to address, please email your query to news@thecharlottenews.org.

November has arrived, and with it our holiday season is now just days away. In preparation for Thanksgiving, many of us venture into the woods and fields, searching for plants to decorate our tables and doorways. One of the most spectacular and sought after plants is the colorful Oriental or

Bittersweet#1 VanVleck in tree

The prolific and fast growing Oriental bittersweet in this mature ash could smother or topple it by the increasing weight of the vine. Note that the bittersweet retains its yellow leaves while the ash leaves have fallen. Photo: Mary Van Vleck

Asian bittersweet vine (Celastrus orbiculatus), which, after growing all summer long, produces a profusion of brilliant orange fruits with yellow-orange hulls. With the orange and yellow side by side, these vines are truly spectacular, and for years people have picked or purchased them for the holidays. As our climate continues to warm, there is more bittersweet around than ever. It thrives in all the New England states, south to Georgia and west to Michigan and Illinois.

This plant is a close relative of our native bittersweet (Celastrus scandens). It was imported from Asia—a native of China, Korea and Japan—and is not a “native” here but rather an “exotic.” And because it reproduces rapidly and outcompetes our native plants, it is considered “invasive.” So how to tell the difference? The leaves of the native and the Oriental bittersweets closely resemble each other, but once the flowers and fruit appear, you can distinguish the native from the exotic quite easily: the fruits of the Oriental bittersweet are located in the leaf axils, where the leaves attach to the stem, whereas the flowers and fruit of the native bittersweet are clustered at the tips of the branches.

So what’s the problem about that? When we pick Oriental bittersweet and bring home those colorful vines, we help this plant to spread. Even when we are careful, the fruits have means of getting back into the ground, where new plants inevitably sprout. Many seeds inevitably drop off when transported from one place to another, and if the vines are left outside, on a door wreath for example, the birds will come and pluck off the fruit. They digest the flesh around the seed and then defecate the still-viable seeds wherever they fly next.

Bittersweet#2 VanVleckIn the fall, the Oriental bittersweet becomes increasingly obvious once the native trees have dropped their leaves because, like many invasive plants, it keeps its now bright-yellow leaves longer than do our native plants. It forms great mats along the forest floor, crowding out other plants there and depriving others of light; and being prolific climbers, it climbs into any nearby tree, encircling the trunk and branches, reaching to the tree tops. As they grow, these circling vines will strangle a tree or branch, and when they get large and very heavy, branches will break or entire trees will topple over under their weight. The vines also grow from one tree to the next, forming a formidable network of tangled branches, a real challenge for any logger or anyone working in the woods.

So this is a real dilemma: we can work to limit the spread of Oriental bittersweet, but we will never eradicate it entirely. In time we can hope that no one will sell it. It may become illegal to sell once its invasive qualities are more broadly acknowledged. In the meantime, as you decorate your homes for Thanksgiving, if you decorate with bittersweet, please remember that you don’t want to add the vines to your compost piles nor should you toss them in the woods. The best of all choices might be to burn it or add it to your garbage where it should do no harm in a landfill, but even that may prove a poor choice over time. If you wish to learn more, there is plenty of information on the Web. In the meantime, we wish you a joyous and colorful holiday season.

Mary Van Vleck is a new member of the Charlotte Conservation Commission.  She lives in the Common Pastures Cohousing community on Greenbush Road.

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