Which biennial weed is known for causing severe blistering and peeling in the sun if its sap contacts the skin?

Wild parsnip is known for causing severe blistering and peeling of the skin when its sap comes into contact with sun-exposed areas. This plant contains a compound called psoralen, which can trigger a severe phototoxic reaction. When the sap of wild parsnip is exposed to sunlight on the skin, it can lead to intense burns and blistering.

This characteristic makes wild parsnip particularly hazardous to those who may handle it without proper protective gear, emphasizing the importance of identifying and managing this weed in right-of-way areas. In addition to its harmful effects on humans, wild parsnip is also an invasive species that can outcompete native plants, further justifying the need for proper identification and control measures in land management practices.