Devil’s Trumpet, (Datura fastuosa), also called Datura metel is native to India and southeast Asia, but now grows all over the world in warm climates. It is in the Nightshade family. I took the photo for this article near the butterfly garden at the Arizona-Sonora Desert Museum. Other common names for this plant include: Horn of Plenty, Downy Thorn-Apple, Hoary Thorn-Apple, Purple Thorn-Apple, and Thorn-Apple. See more photos here.
The plant can be both an annual and perennial and can grow three to 12 feet high. The flowers, which are up to eight inches long, come in a variety of colors including white, yellow, cream, red, and violet.
According to Wikipedia:
All parts of Datura plants contain dangerous levels of highly poisonous tropane alkaloids and may be fatal if ingested by humans or other animals, including livestock and pets.
Datura metel may be toxic if ingested in a tiny quantity, symptomatically expressed as flushed skin, headaches, hallucinations, and possibly convulsions or even a coma. The principal toxic elements are tropane alkaloids. Ingesting even a single leaf can lead to severe side effects.
The plant is cultivated as an ornamental and for its medicinal characteristics. It is widely used in traditional Chinese medicine.
An article in the Journal of Pharmacology goes into great detail about the medical uses of this plant. In summary, “The dried leaves, flowers and roots were used as narcotic, antispasmodic, antitussive, bronchodilator, anti-asthmatic and as hallucinogenic. The plant was also used in diarrhea, skin diseases, epilepsy, hysteria, rheumatic pains, hemorrhoids, painful menstruation, skin ulcers, wounds and burns. In Ayurveda [an ancient medical treatise summarizing the Hindu art of healing and prolonging life], the plant was considered bitter, acrid, astringent, germicide, anodyne, antiseptic, antiphlogistic, narcotic and sedative.”
An article at Entheology.com goes into detail about traditional uses of this plant, most of which involve inebriation.