Parsnips are not only a root vegetable, but also a common weed in Illinois. Unfortunately, wild parsnips also cause allergic reactions in some people. Knowing how to identify wild parsnips can help prevent skin problems later.
Wild parsnip is found growing along roadsides and in non-crop areas. It is typically two to five feet tall and has a yellow flower. Parsnip is closely related to and therefore has the same look as Queen Anne's lace, but with yellow instead of white flowers. This website has pictures and more information on identifying this plant http://www.illinoiswildflowers.info/weeds/plants/wild_parsnip.htm.
Unfortunately, wild parsnip causes skin problems for some people. I remembers my sister having burn-like blisters as a kid from parsnip exposure. Wild parsnip causes phyto-photodermatitis: an interaction between plants (phyto) and light (photo) that induce skin (derm) inflammation (itis).
In other words, touching the leaves makes some people burn and blister. In cases of mild exposure to wild parsnip, affected areas turn red and feel sunburned. In severe cases, the skin first turns red and then forms blisters.
Wild parsnip burns differ from the rash caused by poison ivy in several aspects. First, everyone is sensitive to wild parsnip and you do not need to be sensitized by a prior exposure to develop burns or blisters. You can brush against wild parsnip plants and not be affected. Parsnip is only dangerous when the plant sap from broken leaves or stems gets on your skin. Lastly, the wild parsnip's "burn" is usually less irritating than poison ivy's "itch." The worst of the burning pain caused by wild parsnip is usually over within a couple of days while the rash and itch of poison ivy can last a long time.
The burning sensation can be relieved by covering the affected areas with a cool, wet cloth. Try to delay blisters from rupturing as long as possible as blisters protect the skin by keeping it moist and clean while the areas heal. For those cases with extensive blistering, consult a doctor.
Follow these tips to avoid exposure. Wear gloves, long pants, and long-sleeved shirts. Plan weed control activities for the early evening to minimize sunlight and thus activation of the blistering process. If you are exposed to the plant juice, wash the contaminated areas thoroughly as soon as possible.
Wild parsnip has many other close relatives, none of which cause a parsnip burn. Another relative with yellow flowers is the meadow parsnip. Most other relatives have white flowers. These include the ten-foot tall cow parsnip and the deadly poisonous poison hemlock and water hemlock. Poison and water hemlock both have purple spots or patches on their stems.
Information on how to manage this weed is found at https://www.dnr.illinois.gov/INPC/documents/vmg/VMG%20Wild%20parsnip%20revised%202007.pdf
Yes, wild parsnip is related to the cultivated parsnip. This root vegetable looks like a large, white carrot and is fully edible. For more information on this or other horticultural issues, contact your local Extension office by visiting www.extension.illinois.edu.