It is native to Europe and Asia, and widely naturalised elsewhere, including North America, where it is an invasive problem weed. It occurs in a very wide range of habitats, from woodlands to scrubland, hedges and marshes. It is an invasive species in the Great Lakes region and was first spotted in 1843.
Bittersweet is a semi-woody herbaceous perennial vine, which scrambles over other plants, capable of reaching a height of 4 m where suitable support is available, but more often 1–2 meters high. The leaves are 4–12 cm long, roughly arrowhead-shaped, and often lobed at the base. The flowers are in loose clusters of 3–20, 1–1.5 cm across, star-shaped, with five purple petals and yellow stamens and style pointing forward. The fruit is an ovoid red berry about 1 cm long, soft and juicy, but edible for birds, which disperse the seeds widely.
Bittersweet is used in naturopathy and herbalism. Its main usage is for conditions that have an impact on the skin, mucous membrane and the membrane (synovial membrane) around the joints. Bittersweet is considered by some to be a herbal remedy for treating herpes and allergies.
Description taken from Wikipedia: http://en.wikipedia.org/wiki/Woody_nightshade