The dangers of such plants are known to all through trial and error a very long time ago.
Many food plants contain similar toxins in some parts of the plant.
Most of the nightshade family are poisonous and the family includes potatoes, which are poisonous if green, and tomatoes, the entire plant of which is poisonous, except the fruit. The poisons that lurk in natural foodstuffs Everyone knows about poisonous plants, deadly nightshade, foxgloves and yew, but the sheer scale of chemical warfare waged by natural creatures, both plants and animals, comes as a surprise. Even in Britain, a high proportion of the common plants is poisonous to a greater or lesser degree. The reason is that poison is a countermeasure in the struggle for life. Plants are poisonous to prevent them being eaten and the reason more people aren't poisoned is that most poisonous plants taste very bad.