Good question! (And nice pics! Your day looks gloomy like ours.)
Wiki answers your question:
It has colorful, orange fruits that are the size of a pea. These fruits are poisonous to humans when ingested internally, but are favorites of birds. C. scandens roots were used by Native Americans and pioneers to induce vomiting, to treat venereal disease, and to treat symptoms of tuberculosis.
C. scandens is native to central and eastern North America. It was given the name Bittersweet by European colonists in the 18th century because the fruits resembled the appearance of the fruits of Eurasian Nightshade (Solanum dulcamara), which was also called Bittersweet. Today, American Bittersweet is the accepted common name of C. scandens in large part to distinguish it from an invasive relative, C. orbiculatus (Oriental Bittersweet), from Asia.