More on "Poison" Parsnip

Around the house area and in spots around the property there is a high density verging on monoculture of Wild Parsnip [Pastinaca Sativa]. As a youth I remember this as poison parsnip which was abundant in the fallow fields around our houses in the suburbs of Montreal where I lived in the 60’s. If you touched the leaves it could leave you with a very itchy rash. After much Internet research, I found that the juice of the plant is only irritating to the skin when exposed to UV (Sun) light. Indeed if I cut the weed in the evening just before dark and get the sap on my skin I would not contract a rash. The worst time is early in the morning on a sunny day. What makes this reaction difficult to diagnose is that the rash will occur about 4 days after contact, so you would have to remember what you did differently. Also the sap potency would only last a few minutes and become benign when it dries up even on the disturbed leaf. This is unlike poison ivy that lasts much longer.