As we approach the Christmas season, it is not uncommon for folks to use natural plant materials for decorations, such as evergreen boughs, various vines, holly and other plant parts. One that is commonly used is bittersweet. But did you know there are two different kinds of bittersweet?

Exotic oriental bittersweet looks very similar to our native American bittersweet, but it is an aggressive invader of our woods and forests. It has a woody vine and has been around since the mid-1800s. It thrives in a variety of habitats, including roadsides, interior forests, shade, open woodlands, stream sides and old fields. Like most vines, it can overgrow adjacent vegetation and even trees — sometimes actually breaking them down. The attractive bright orange berries appear in fall and are commonly mistaken for American bittersweet.

American bittersweet is a common vine, but it is not an aggressive grower like oriental bittersweet. It also has larger fruit than its exotic competitor. To complicate things, both species can hybridize.

So, if you want to use American bittersweet as a holiday decoration, how can you tell the difference? The two most reliable plant characters are the fruit and leaves. If the leaves are not present, you will have to rely on the fruit and the position of the fruit on the stem.

With oriental bittersweet, the fruit is situated where the leaf axils were and along the length of the stem. Also, the capsules that surround the fruit are yellow. For American bittersweet, the fruit tends to be positioned at the tip of the stem in clusters. Fruit capsules of American bittersweet are orange. The number of seeds in the fruit is also different, with oriental bittersweet having five or more while American bittersweet generally has one seed.

If some leaves happen to be present, oriental bittersweet leaves are alternate and elliptical with finely toothed margins, and turn yellow in fall. American bittersweet leaves are more rolled like a scroll, and elongate coming to a pointed apex.

Fight the spread

Because oriental bittersweet is very aggressive — and because the seeds can be spread by birds and animals that consume the fruit, and by humans collecting the fruit and decorative vines — early control is very important. Simply pulling up the vines is not sufficient, as the roots will resprout. Use of fire may kill young seedling, but will only damage larger, mature plants, which will stimulate root suckering. Basal bark sprays and cut stump treatments must be used in conjunction with mechanical efforts to ensure effective control. Simply pulling up the vines will not be effective without application of herbicides.

Like with any invasive, it is important to catch oriental bittersweet early, avoid spreading the plant and plant parts, and encourage the use of native, noninvasive species.

If using vines for decorations is really your preference and specialty, suggested alternative vines would be Dutchman’s pipe (Aristolochia durior), native Illinois Dutchman’s pipe (A. tomentosa) or Virginia creeper (Parthenocissus quinquefolia), along with American bittersweet.

While it may be fun and novel to use plants and plant parts for your holiday decorations, be sure you are picking the right plants, and be sure to dispose of them properly to prevent their spread.

Miller is a horticulture professor at Joliet Junior College in Joliet, Ill., and a senior research scientist in entomology at The Morton Arboretum in Lisle, Ill. Email your tree questions to him at [email protected]. The opinions of this writer are not necessarily those of Farm Progress/Informa.