deadly nightshade - Atropa belladonna - aka Devil's cherries, belladonna, dwail, and dwayberry amongst other names.
Belladonna
In Italian, a beautiful lady; in English, a deadly poison.
A striking example of the essential identity of the two tongues - The Devil's Dictionary
Deadly nightshade belongs to the Solanaceae family, a family of plants which includes the humble potato and chilli pepper, and the more fascinating mandrake (Mandragora officiarum) and henbane (Hyoscyamus niger). It is a poisonous plant which has purportedly been used on many an infamous occasion including the assassinations of Roman Emperors Claudius and Augustus and the overwhelming of the whole Danish army when the Scots drugged their stores of ale. The toxicity is due to the presence of the alkaloids hyoscyamine, scopolamine and atropine, but these substances also have valuable scientific and medical uses, resulting in the widespread cultivation of Atropa belladonna .
All parts of the plant are deadly poisonous, whether ingested, absorbed through the skin or even eaten inadvertently by eating an animal which had consumed it. The name Atropa is derived from Greek mythology - Atropos, the Fate who held the scissors which could cut the thread of human life. Belladonna, or beautiful lady, apparently comes from the plant's use (suitably diluted) as a cosmetic which dilated pupils and made women look more attractive. The Old English name dwail is thought to come either from the Dutch word meaning delerious or the French deuil meaning grief.
Deadly nightshade is common in Europe, England and the USA. It is primarily a weed found growing on wasteland, woods and in chalk or limestone areas. The plant is a low growing shrub reaching up to 6 feet, but more commonly about 2-3 feet. The tops dies down in winter but it regrows from thick fleshy roots the following spring. The stems are purplish-green and branched, the leaves are dark green and oval in shape. The plant produces purple, bell-shaped flowers in summer which develop smooth, round, black berries about the size of a small cherry. The berries are very sweet - and poisonous to humans - just one or two can be fatal in a child. Deadly nightshade is sometimes confused with Bittersweet Nightshade
Solanum dulcamara, but this is a vine which bears red berries.
Ingestion of deadly nightshade produces a number of symptoms depending on the quantities eaten. The overdose level is around 600 mg and symptoms begin to occur within 30 minutes; these include dilated pupils, dryness of the mouth, nausea, vomiting, depression, increased heart rate, muscle failure, delirium, exhaustion, hallucinations, general paralysis, coma and death due to respiratory failure. These effects are, however, put to good use medically - atropine is a very useful drug in the treatment of asthma, gastric ulcers,brachycardia and most importantly in Parkinson's Disease. Historically a mixture of hemlock, belladonna, mandrake and henbane applied to the skin would have been used as an anaesthetic in childbirth and prior to operations.
http://www.siu.edu/~ebl/leaflets/atropa.htm
http://www.cnr.berkeley.edu/~reynolds/Luna/FromTheWitchesBrew.html
http://www.erowid.org/plants/belladonna/belladonna.shtml