Decorating for the holidays can bring joy to households, and putting your decorations up early could make you happier, but watch out for Oriental bittersweet (Celastrus orbiculatus)! If you are a DIYer or like to craft your wreaths or other holiday decorations using materials from your backyard or local outdoor environment, you may be mistakenly causing harm to the environment and creating future landscaping challenges for yourself and neighbors. Oriental Bittersweet is covered with bright red fruits and yellow capsules, making this vine alluring, but according to the UNH Cooperative Extension service, the vine is also highly invasive and poses a significant threat to native plants.
Oriental bittersweet is native to Eastern Asia and was intentionally introduced to the United States in the mid-1800s as ornamental landscaping and for use in erosion control because it is both pretty and effective; it is fast-growing, spreads easily and is not finicky about soil or water conditions. Oriental bittersweet has escaped cultivation because it grows in full sun as well as shade, and in many different locations including meadows and grasslands, woods and woodland edges, along roadsides and even on dunes and beaches! After the invasive species made its way to New Hampshire in 1938, by the 1970s it was recognized as an aggressive invader, and by 2011 it was widespread across New England. It is now found throughout 21 of the 33 states where it was introduced, a region extending from Maine south to Georgia and west to Iowa.
Wherever Oriental bittersweet is found, it grows very rapidly, wrapping around trees, damaging, and sometimes suffocating or killing them. The vines can uplift tree roots and can take down trees that reach 90 feet in height. The extra weight on the trees can cause limbs to drop and contribute to power outages or cause damages.
Try American Bittersweet
When making holiday decorations or wreaths, a good alternative to Oriental bittersweet is American bittersweet (Celastrus scandens), but this species is less widespread in New Hampshire and is typically found only in landscaped locations actively maintained by a homeowner, since it cannot compete with Oriental bittersweet in areas that are not maintained such as roadsides and open wooded areas. The two species can be easily confused because they are similar in color and appearance. Oriental bittersweet fruit (pictured below) has a bright yellow outer covering with red centers, is located along the vines in leaf axils and has bright, yellow colored leaves in the fall that are easy to see. American bittersweet fruit (pictured below) can sometimes have a yellow outer covering but tends to be more orange or even red over a red interior and tend to cluster at the stem’s end.
Another good decorative option that may be available locally is winterberry (Ilex verticillata) – this species (pictured right) is easily noticeable in the swamps, wetlands, damp wood edges, and along the edges of ponds and streams throughout New Hampshire. Showy, clustered red berries pop out from the vegetation in the late fall, and, different from bittersweet, persist on branches well into the winter months, explaining how winterberry got its name. It is often considered one of the best plants for providing winter interest in the garden.
Ask for Help at Garden Centers
If you are cutting your own vegetation to use in holiday decorating, take the time to look further than roadsides, since those habitats tend to be invaded by Oriental bittersweet, or consider asking for scraps at garden centers or local nurseries since they may have remnant cuttings of native plants for free or low cost. Maybe even think about your holiday decorating in the summer and fall, so that while you walk, run, hike or explore your local surroundings, you can keep an eye out for winterberry, holly or American bittersweet locations.
I Already Have Oriental Bittersweet – Now What?
Don’t worry, you can save the trees and your holiday spirit! If you see Oriental bittersweet in your holiday decorations, the best thing to do is throw it away. You can also burn it in your fireplace or woodstove. It’s best to avoid throwing it outside or composting since the fruit, or “berries” can survive through winter and will create new vines in the spring. If DIY isn’t your area of expertise, remember to ask when you purchase decorations with berries if they are real or plastic, and if they are real, where they came from, and does the seller know which species they are? Again, if you are ever unsure, best to throw them in a fire rather than outdoors to prevent the unintentional spread of invasive species.
Reach out to our Senior Environmental Coordinator Kimberly Peace if you’d like more information.