The Carlisle Mosquito Online

Friday, December 13, 2002


Oriental bittersweet

It's Friday the 13 and some unlucky worms became breakfast this morning for the early birds. In another unlucky turn of events, back in the mid-to-late 19 century, perhaps on a Friday 13th, the Oriental bittersweet was deliberately introduced into America beginning a story of unintended consequences.

Photo by Tom Brownrigg
Name: Celastrus orbiculatus or Oriental bittersweet; also known as Asiatic bittersweet. The bittersweet vine turns out to be aptly named. There is sweetness in the seductive good looks of the colorful berries in the fall and winter. The bitterness is that the vine is invasive; it can damage desirable plants by strangling them or by blanketing them and limiting photosynthesis; it is displacing the native bittersweet through both competition and hybridization.

When and where seen: Can be seen throughout the year but is easiest to notice in the fall and winter when the red berries with their yellow jackets stand out in the landscape. It can be found in many places in Carlisle along the roadside and in the Towle and Greenough land. It is also frequently seen in floral arrangements and wreaths at Thanksgiving and Christmas. It is native to eastern Asia, Japan, Korea and China.

Description: Oriental bittersweet is a vigorous, deciduous, perennial, woody vine. It climbs to heights of 36 feet by twining around its support. The leaves are glossy, finely toothed, variable in shape but frequently rounded, and arranged alternately along the stem. The vine is usually dioecious (male and female flowers on separate plants). The flowers are greenish-yellow and inconspicuous. The glory is in the fruits which ripen from green to bright yellow. When mature, the yellow coating splits open, folds back, and exposes the three red fleshy arils which contain the seeds.

Look-alike: The native bittersweet, Celastrus scandens, flowers and bears fruit in terminal clusters while the oriental bittersweet flowers and fruits along the stems. The Nature Conservancy reports that many nurseries sell Oriental bittersweet mislabeled as Celastrus scandens.

Control: Several methods of control are available: reduction in proliferation by nurseries through education, careful disposal of seeds from floral arrangements, weekly mowing, and the application of a systemic herbicide (like Roundup) to the stem tissue of freshly severed stems.

Alternative plants for landscaping: For vines attractive to birds, consider the native bittersweet, the trumpet creeper (Campsis radicans), or Dutchman's pipe (Aristolochia macrophylla). For berries, consider some of the native hollies, like Ilex verticillata which is available in a compact form, or Ilex opaca, the American holly tree. For general winter interest, consider trees with patterned or exfoliating bark like the Paperbark Maple, the Striped Maple or the Lacebark Pine.

References: Glenn D. Dreyer, Elemental Stewardship Abstract for Celastrus orbiculatus, The Nature Conservancy,;

Submissions for the Biodiversity Corner are encouraged from everyone. Please feel free to write up a species for the Christmas season. Seen any holly or partridges in pear trees? If you have a mystery species and want help with identification, send a photo and some field notes to Kay Fairweather at 392 School St, Carlisle MA 01741 or to

2002 The Carlisle Mosquito