was curious about the plant so I looked it up! (from wikipedia):
Atropa belladonna or Atropa bella-donna, commonly known as Belladonna, Devil's Berries, Death Cherries or Deadly Nightshade, is a perennial herbaceous plant in the family Solanaceae, native to Europe, North Africa, and Western Asia. The foliage and berries are extremely toxic, containing tropane alkaloids. These toxins include scopolamine and hyoscyamine which cause a bizarre delirium and hallucinations,[1] and are also used as pharmaceutical anticholinergics.
It has a long history of use as a medicine, cosmetic, and poison. Before the Middle Ages, it was used as an anesthetic for surgery, the ancient Romans used it as a poison
Atropa belladonna, along with related plants such as jimson weed (Datura stramonium), have occasionally been used as a recreational drug because of the vivid hallucinations and delirium that it produces. These hallucinations are most commonly described as very unpleasant, however, and recreational use is considered extremely dangerous because of the high risk of unintentional fatal overdose.[29][30][31] In addition, the central nervous system effects of atropine include memory disruption, which may lead to severe confusion.[32]
In the past, it was believed that witches used a mixture of belladonna, opium poppy, and other plants, typically poisonous (such as monkshood and poison hemlock) in flying ointment they applied to help them fly to gatherings with other witches. Carlo Ginzburg and others have argued that flying ointments were preparations meant to encourage hallucinatory dreaming
also this site
http://www.alchemy-works.com/atropa_belladonna.html (look at the name of the site!)