Belladonna. Historical artwork of the leaves and flowers (blue/purple) of the belladonna plant (Atropa belladonna). Also named deadly nightshade, this is a poisonous plant that is used in herbal medicine. Chemicals from this plant are also used in modern medicine to dilate the pupil of the eye and to treat intestinal disorders. Engraving from an Austrian natural history book published in 1853 (Naturselbstdruck).