Plant of the Week: False or American Bittersweet

Birdwatchers appreciate this native vine for a source of emergency food late in the winter.  Arts and craftsmen appreciate it this time of the year for making wreaths and decorating, adding that brilliant orange color to the fall palate of reds and yellows of the turning leaves.  Landscapers, naturalists, and ecologists have come to hate it because they confuse the native vine with oriental bittersweet, which is invasive and a major pest species in this state and numerous others.  It is far more invasive than the native species because the berries are more red than orange and eaten more by birds, there are more of them on the vine than the native species, and the seeds have higher germination rates.  What this has led to is a decrease in the native species and an increase in the exotic species. The invasive will grow at the base of the tree and over time will eventually girdle the tree, killing it (just like English Ivy does) and in some extreme cases, the vines become so heavy with berries that they actually uproot smaller trees. Oriental bittersweet is now a problem in every single Kentucky county and the problem is getting worse.  On the flip side, I have noticed, although just through observation and not scientific research, that the native vine is decreasing and becoming harder to find in the wild.  To make matters worse, it appears that the oriental version can hybridize with the native species causing further ecological issues. So let's help nature out by planting this lovely native vine.

The true native vine is actually called false or American bittersweet, Celastrus scandens, and it can be difficult to identify when compared to the exotic, invasive oriental species (C. orbiculatus).  When you look at the leaves, typically the Asian variety are more rounded and less pointed with the native species having longer leaf tips.  The edges are typically more jagged than in the Asian species. While leaf shape is somewhat distinguishing, the best method of telling the two species apart is that the emerging leaves in the Asian species are folded whereas in the native species they are rolled like a scroll. If you have plants that are in flower, the best method is to examine pollen color (oriental white, American yellow).  In the fall, the best method is to note that fruit only occurs in a terminal cluster in the American species and oriental has fruit in the axils of the leaf along the stem.  The fruit in the oriental species is also typically larger and has more seeds in it.  Of course both spring and fall are excellent times to control Oriental bittersweet with herbicides.

This is a very adaptable, deciduous vine that will tolerate most any soil type, even clay and will grow in full sun to full shade, although to get maximum fruit production you would need to place it in full sun. The vine is dioecious with male flowers on one plant, female on another.  To get good fruit production you would need to place a male close to a female plant for pollination. The primary pollinators are bees which are attracted to the flowers in May and June.  The only maintenance required is to do a little pruning in early spring or late winter to keep the vines neat and tidy.  This is a fairly easy species to propagate from seed or cuttings.  The most reliable method of getting male or female plants is through cuttings of a known sex.  This species is widely available in the trade and make sure you get the native variety, which is prettier anyway, than that nasty Oriental species.