Death to the Wild Parsnip!

Everyone knows that you should stay away from poison ivy.  Many people even know what it looks like.

Hint:  (image from http://www.wikihow.com/Identify-Poison-Ivy).

Many people have also heard of poison oak and poison sumac, and know to stay away from them as well.  But are you aware of the danger that the wild parsnip can pose?

The stem and leaves of the wild parsnip (essentially the same plant as the cultivated parsnip that we eat) contain chemicals called furocoumarins.  These chemicals are not strictly speaking dangerous on their own, but when they are absorbed into the skin, through contact with a broken plant, they can react to ultraviolet light (from the sun, presumably) and damage the nearby cells, essentially acting as a sunburn accelerant.  The problem is complicated by the fact that the damage typically takes a day or two to show up, so often a victim will just sort of spontaneously develop a burn and have no idea why.

The good news, such as it is, is that the burns aren't even as bad as poison ivy, most of the time.  If it does happen to you, keep it clean and loosely covered.  The blisters will fade pretty quickly.  And of course, if you do manage to recognize the plant, washing yourself off promptly will help a great deal.

Source: http://dnr.wi.gov/wnrmag/html/stories/1999/jun99/parsnip.htm