I’ve previously featured deadly nightshade in fruit, so that entry contains some background on this poisonous plant. The epithet belladonna translates to “beautiful lady”. The reason commonly cited for the name is the attractiveness caused by the pupil dilation that accompanies an application of atropine to the eye (this technique was used centuries ago as part of make-up preparations).
I’m not entirely convinced, though, as I have a suspicion that the name predates that practice. Perhaps it has more to do with the legend of the plant metamorphosizing into a woman (this phrase formerly linked to a now-defunct site) on Walpurgis Night. Or, perhaps it was the Roman equivalent of “beer goggles”, where nightshade-laced wine had the effect of reducing inhibitions and inducing hallucinations.
As Stephen Howser explains in this article on Atropa belladonna for the Southern Illinois University Herbarium, deadly nightshade has had other uses besides beauty and parties. It could be considered one of the first chemical weapons, as Romans used it to poison enemy food supplies. Contrarily, it was also developed as an antidote to a (never deployed) nerve gas in World War II. Historically, it was also blended with other plants to create a local anesthetic.