The poisonous aspects of wild parsnip can be explained in a single word: phytophotodermatitis.

Latin words used as science terms are a shortcut to writing many sentences to say the same. But one has to know a bit of Latin, or the term becomes nonsense.

There are three parts to phyto-photo-dermatitis.  Phyto means plant; wild parsnip in this instance.  Photo means light; sunlight here.  And dermatitis refers to the skin becoming inflamed or blistered when the plant juices and sunlight come together.

When the plant's juices get on someone's skin, the skin becomes more sensitive, or hype...