Asian Bittersweet

Celastrus orbiculatus [ CISMA, USDA, Wikipedia, GoBotany ]

Asian Bittersweet, the "northern Kudzu", is pervasive around Acton. This aggressive vine tolerates both high sun and deep shade, and can quickly overtop and girdle trees. While normally a climbing vine, it is woody enough to grow into a bush shape. In mature infestations, the vine may be several inches in diameter and have a rough bark. Its bright red berries are eaten by birds and widely spread.

It is found on all Acton conservation lands.

Removal

There is a multi-step approach to combating Asian Bittersweet. The first step is to cut the vines "high and low" to prevent seed generation and tree death. The low cut should be around a foot off the ground, and the high cut should be as high as possible.

The second step is to try to uproot the stems left behind. Asian Bittersweet has a distinctive orange root. There will be at least two roots where it enters the ground, heading in opposite directions. The main root/vine may run for twenty or more feet before reaching the main root cluster. If a vine can't be uprooted, it should be cut in several places. It will come back from the smallest root fragments. Cleaned areas will require re-clearing every year for several years, to eliminate regrowth from roots. If no uprooting was done, multiple visits a year should be done to cut regrowth from the cut stems.

An alternate technique used by the Land Stewards when the roots cannot be removed (e.g. stone walls in the Wright Land, or under fir trees in the Concord Rd. Playing Fields) is to cover the area with thick black plastic, with something to hold it in place (e.g. wood chips), and leave it in place for two years. Once pulled, the vines and roots may be left locally in a brush pile to decompose. If roots are left in water, they might regrow so direct ground contact is to be avoided.

Common Mis-Identifications

There is an American Bittersweet (Celastrus scandens) [ USDA, Wikipedia ] differentiated by a longer leaf and flowers/berries only at the end of branches. Unfortunately, it readily hybridizes with Asian Bittersweet (Flora Novae Angliae)

Native grapes such as Fox Grape (Vitis labrusca) [ USDA, Wikipedia ] and Summer Grape (Vitis aestivalis) [ USDA, Wikipedia ] have stems and leaves are distinctly different, but tend to grow in the same locations as Asian Bitterweet. Be careful not to remove them when removing the bittersweet.

Other native vines growing up trees, like Poison Ivy, Virginia Creeper, or Boston Ivy (a.k.a Japanese Creeper, and non-native although not very invasive in Massachusetts), attach themselves to the tree using trendrils that work themselves into the bark. Asian Bittersweet only attaches itself by wrapping around its victim.