Black nightshade. Note short calyx
Photo courtesy Dean Swan, Washington State University (retired)

Hairy nightshade with calyx cupping the berry. 
Photo courtesy Dean Swan, Washington State University (retired)

• Climbing nightshade (Solanum dulcamara), also known as bittersweet: perennial with long branches trailing or climbing on other plants; lance-shaped leaves lobed at the base; bluish-purple flowers; immature green berries turning bright red

• Hairy nightshade (Solanum sarrachoides): annual to 0.6 metres tall; white flowers; dense covering of short hairs on leaves and stems; yellowish-brown berries at maturity; calyx cupped 2/3 around berry

• Black nightshade (Solanum nigrum): annual to 0.9 metres tall; white flowers; smooth leaves; black to dark purple berries at maturity; short calyx does not cup the berry
• young plants and immature berries are particularly poisonous