Sacred Datura

Description:

All parts of this plant contain the tropane alkaloids scopolamine, atropine, and hyoscyamine. These chemicals are anticholinergics, agents that block the neurotransmitter acetylcholine in the peripheral nervous system. Low doses result in delirium and hallucinations. Very high doses are accompanied by many negative effects, eventually leading up to seizures, coma, and possible death. Low doses of atropine are used in ophthalmology to dilate the patient's pupils. It is also an effective treatment for bradycardia (low heart rate).

Notes:

Many more medicinal uses listed on the Wiki page.