Prevent infestations, avoid invasive holiday decorations

Adorning your home with lights, garlands and wreaths can add warmth and beauty during this festive season, and live or dried plants can be especially pretty. When using plants, however, there are some important things to keep in mind. Invasive plants such as invasive Phragmites (Phragmites australis, subspecies: americanus), invasive bittersweet (Celastrus orbiculatus), cutleaf or common teasel (Dipsacus laciniatus or D. fullonum) and baby’s breath (Gypsophila paniculata) are often added to holiday decorations that can be sold locally and online. The improper disposal of these decorations can promote the spread of invasive species and subsequent degradation of the ecosystems we all enjoy.

None of the above invasive plants are common in the Keweenaw yet, and you can help keep it that way. Knowing which plants to look out for can be the first step.

Online resources are so convenient for shopping, but a quick search in Etsy can bring you aesthetic wreaths made of bittersweet and dried flower bouquets of Phragmites, baby’s breath, and teasel seed heads. One of the most commonly used plants for decoration is invasive bittersweet, which is described by the USDA Forest Service (https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/fsbdev3_017307.pdf). While invasive bittersweet’s yellow capsules and red berries look attractive and festive, its seeds last for several years, so even when you are ready to toss them in your compost, they could germinate.

Likewise, invasive Phragmites seed heads are attractive, fluffy plumes and are full of seeds that are poised to invade shorelines. The Great Lakes Phragmites Collaborative is an excellent source for protecting our shorelines from the problems caused by invasive Phragmites (https://www.greatlakesphragmites.net/). These two plants not only outcompete our natives for resources, but they can damage our landscapes in a lot of ways. Bittersweet climbs up trees eventually smothering them, and Phragmites creates monocultures that can grow up to 15 feet tall, blocking waterfront views and harming fish and bird habitat.

Teasel is another frequent plant in decorative flower arrangements, mentioned by Matthaei Botanical Gardens and Nichols Arboretum (https://www.mass.gov/news/avoid-decorating-with-invasive-plants). Buying these decorative arrangements and bringing them to the Upper Peninsula could introduce a new species like teasel. Teasel is currently widespread in southern Michigan and Wisconsin and further south and can outcompete native plants by producing over 900 seeds per seed head.

According to Dr. Daniel Simberloff in his book, Invasive Species: What Everyone Needs to Know, invasive species can be accidentally introduced in numerous ways, varying from ornamental plantings to hitch hikers on shoes, but a possible way that teasel could be introduced up here is through the transport of the seed heads for decorations (http://dx.doi.org/10.1093/

wentk/9780199922017.001.0001). For more information on some common invasive plants used for holiday decorations, visit Wisconsin’s Department of Natural Resources article, https://dnr.wi.gov/news/Weekly/Article/?id=4388.

Prevention is the cheapest alternative to protecting our area from invasive species. Since we are well into the holiday season, you might already have these plants in your home. There are a few simple steps you can take to ensure your decorations do not invade here. Wreaths hung outside may be eaten by birds, who spread seeds as they fly. If your wreath has bittersweet or another berry that could be invasive, try to hang it inside. When the holiday season comes to an end, you can either burn things that could contain seeds, or bag them in a trash bag and throw them away. Further prevention steps can include decorating your house and yard with native plants such as pines, firs and spruces. For some of those festive red berries, consider growing winterberry (Ilex verticillata), which is a native shrub that is important for wildlife.

Contact kisma.up@gmail.com or visit KISMA’s website at https://www.mtu.edu/kisma/ with any invasive species concerns.

Haniya Frayer is an undergraduate student in Applied Ecology and Environmental Science at Michigan Technological University (hefrayer@mtu.edu); Dr. Sigrid Resh is Coordinator for the Keweenaw Invasive Species Management Area (scresh@mtu.edu)


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