Deadly nightshade is a term used to describe three different plants: BELLADONNA, petunia, and henbane. BELLADONNA, also known as deadly nightshade, is a perennial herbaceous plant with 10 letters in its name. Petunia is a genus of flowering plants with 7 letters in its name, and henbane is a poisonous plant with 7 letters in its name. All three of these plants are highly toxic and can cause serious health problems if ingested.