Contact(s): Matthew Wallrath, WDNR organisms in trade outreach coordinator, 608-266-8916; email@example.com
MADISON - Homeowners and decorators creating their autumn displays should avoid two invasive plants that have been used historically in Thanksgiving and other floral arrangements but are increasingly recognized as harmful to forests, wetlands, prairies, and other wild areas.
Oriental bittersweet and multiflora rose offer attractive red accents but their use in holiday decorations and their disposal in compost piles increases the risk that these invasive plants will spread to new sites, says Matt Wallrath, Wisconsin Department of Natural Resources outreach coordinator working with the plant nursery, aquarium, pet, and bait industries to prevent the sale and distribution of invasive species.
"Our wild lands and conservation areas are threatened by these non-native plant species, which can outcompete native plants and displace native wildlife," Wallrath says. "Vendors and consumers should seek native plant alternatives instead and avoid these invasive plants, which are illegal to sell or distribute in Wisconsin."
Oriental bittersweet (Celastrus orbiculatus) is a vine that spreads in forest understories and is known to kill mature trees by strangling their trunks. Multiflora rose (Rosa multiflora) is a shrub that can form impenetrable bramble thickets that impede hunters and other recreationalists, while shading out native plant species.
The colorful fruits of these species are often eaten by birds and dispersed to areas far from their origin. Once established, these species are difficult to control. Even when these plants are cut down close to the soil, they re-sprout from roots remaining belowground.
Kelly Kearns, an invasive plant specialist for the DNR Natural Heritage Conservation Program, suggests that vendors, decorators, and others looking for bright accents should consider using Wisconsin native species including American bittersweet (Celastrus scandens), winterberry (Ilex verticillata), and native roses like smooth rose (Rosa blanda). "Native alternatives can add vivid color without posing a threat to our Wisconsin plants and animals," Kearns says.
To control the spread of invasive species, Wisconsin regulates the importation and sale of more than 140 plants, as well as some animals, that have been identified as invasive in Wisconsin. Oriental bittersweet and multiflora rose are on the list of restricted species on the Wisconsin invasive species rule (Wis. Adm. Code ch. NR 40), making it illegal to transport, introduce, gift, buy, sell, or trade these plants unless you are trying to control or safely dispose of them. Search the DNR website, dnr.wi.gov, for "invasive species rule" to find an interactive list of invasive species, with factsheets, photos, identification tips, and more.