One of the prettiest native North American vines in the autumn, bittersweet vine (Celastrus scandens) provides food for birds and decoration for fall floral decorations and arrangements. In the northeastern United States, this native vine becomes rarer each year as the invasive Asian or Oriental bittersweet vine (Celastrus orbicularis) grows more aggressively and chokes out the native vine's habitat.
The American bittersweet vine hails from eastern North America, from both Canada and the United States. It grows in woodlands, rocky hillsides and bluffs, along stream banks and in thickets. The native range extends from Canada's Quebec westward to Manitoba and then southward into the United States, from Montana and Wyoming to Texas and eastward to northern Georgia.
A sprawling woody vine, bittersweet becomes striking in autumn, when its many small fruits ripen. They are orange-yellow and split open to reveal a red seed called an aril. They develop in drooping clusters from the tips of the stems, unlike those of the invasive Asian bittersweet, which develop all along the vine's length.
The green leaves are oval with teethed edges and do not attain much of a yellow-green or golden color before dropping away in autumn. The tiny summertime flowers can go unnoticed.
Appreciating a consistently moist soil, bittersweet vine cannot tolerate soggy soil conditions. A near-neutral pH (6.8 to 7.2) soil is ideal, but it tolerates slightly more acidic or alkaline soils if it is rich in organic matter and drains water well. Full-sun exposure--at least eight hours of direct sun daily--is best for flowering and fruiting. The vine grows well in partially shaded situations, but fruiting is diminished. At maturity, the vines reach a length of 12 to 36 feet, climbing upward or as a sprawling, rambling ground cover.
Although American bittersweet vine and the Asian/Oriental bittersweet vine can be distinguished by their fruiting display and habits, both species hybridize in the wild. This can make identifying the vines difficult, particularly when gardeners or environmentalists attempt to eradicate the more aggressive Asian species from their formal gardens and natural landscapes. These hybrid vines in effect destroy the native gene pool, making the pure genetic strands of the native bittersweet even rarer and more endangered.
Birds like the seeds for food, but humans must refrain from eating any part of the bittersweet vine, from leaves to fruits. Chewing on the seeds or leaves can cause vomiting and diarrhea, and large consumption can lead to a loss of consciousness.