Prickly Poppy (Argemone, Thorn Apple)

• Common Name: Prickly Poppy (Argemone, Thorn Apple)
• Latin Name: Argemone spp
• Family Name: Papaveraceae

All parts of the Prickly Poppy are toxic, although the seeds are the most poisonous part.  This plant contains the alkaloid sanguinarine, which kills animal cells and is known to cause oedema (edema), liver failure, and could prove fatal so it should be avoided. 

N.B. Thorn Apple is occasionally listed as one of the common names of this plant, and it shouldn't be confused with Datura, which is also called Thorn Apple but is a different plant.