Henbane or Hyoscyamus niger belongs to the solanaceae family. 
Like Datura stramomium, it has a foul smell. Three alkaloids - 
hyoscyamine, scopolamine and atropine can be isolated from the 
plant. Henbane is derived from  Anglo-Saxon words Henn 
(chicken) and Bana (murderer) because when fowls eat the seeds 
of this plant, they become comatose and die. The seeds are also 
the traditional ingredient of witches' brew. All parts of the plant 
are poisonous and if eaten causes delirium and other anti- 
cholinergic effects including mydriasis and cycloplegia. It was 
used to induce sleep as evidenced in an Anglo-Saxon text 
 'in case a man is not able to sleep, take henbane seed and juice 
 of garden mint, shake them together and sear the head therewith; 
 it will be well with it.