The nightshade above (Solanum dulcamara, Solanaceae) has a number of common names. The most widely-used seem to be bittersweet nightshade, climbing nightshade, and woody nightshade. The latter two terms seem the most descriptive; this plant is a semi-woody vine that climbs up other plants. This particular nightshade was making its way up a blue spruce (Picea pungens, Pinaceae):
As with many other members of the family Solanaceae, many parts of this plant are at least mildly toxic. The berries in particular contain non-trivial amounts of the toxin solanine when immature. The mature berries are apparently less toxic and are commonly eaten by birds, who spread the seeds.
The fruit follow from the pollination of the interesting purple flowers that form late in the summer.
Calling this bittersweet nightshade can lead to some confusion, since there are entirely different plants known as bittersweet (Celastrus sp., Celastraceae). This sort of confusion is why Latin names are the definitive names used for organisms in biology.