A Little Bit More
If you want to impress your friends, use Phytophotodermatitis in a sentence and you’re sure to get their attention! As you can see from the poster, by breaking this word down into its basic components, it’s really not that difficult a word.
Although the Wild Parsnip is an alien plant from Europe and Asia, it has been in North America for more than 100 years. Records from Wisconsin alone show that the plant was known to be established in that state as early as 1894. Actually, the Wild Parsnip is found in much of Canada and some area of every U.S. state except Hawaii, Mississippi, Alabama, Georgia, and Florida.
The Wild Parsnip (Pastinaca sativa) is simply the wild form of our cultivated vegetable by the same name. For individuals who are conversant with botanical nomenclature, the Wild Parsnip can be identified from other carrot family members with its 1.) flat-topped compound umbels of yellow flowers, 2.) compound leaves that are single pinnate, rather than doubly pinnate, and 3.) more than 8 teeth on each side of a leaflet. These aliens can be quite large, growing from 2 – 5’ in height and are most common in disturbed areas such as roadsides and waste places.
Chemicals in the juice of Wild Parsnip’s stem, leaves, and fruit are the problem and need to be avoided. If contact is made, a burn is usually obvious within 24 hours and then peaks in severity within 48-72 hours. When these chemicals are absorbed by your skin and then acted upon by ultraviolet light, they cause a breakdown of skin tissue and you’re left with an ugly red, sunburn-like patch or even blisters that may last for weeks. In areas where the plant has become abundant, some landowners have tried pulling and cutting of parsnip in the evening when sunlight on juice-smeared skin is unlikely. If you do get the plant juice on your skin during daylight hours, you should wash your skin as soon as possible.
Activities
Hostile Plants
Objectives: Show students that plants can “fight back”
Materials: Library or internet access
The whole issue of plant defenses is a very complex subject and one that is undergoing a great deal of research. We know that many plants have methods of defending themselves from being eaten whether it be specific structures (thorns or prickers), or specific chemicals that reduce herbivory ( being eaten by an herbivore).
Most of us have heard about plants we shouldn’t eat because they may poison us. Here is a short list of some plants that have developed protective measures to reduce or eliminate being eaten. Have students select one of the following (or go online and select one of the ones there) plants and see what they can find out about that particular plant’s defensive mechanism. You might find it particularly interesting to select those species that are commonly planted in your area (ie. Oleander in the South or Yew in the North). It seems that we actually surround ourselves with many different plants that can be harmful if handled and/or eaten. This exercise may surprise you when you learn that one of your backyard plants is actually a potential hazard if not handled properly.
Some of the plants that have their own built-in defenses:
- Cacti
- Poison Ivy
- Poison Oak
- Stinging Nettles
- Honey Locust
- Hawthorne
- Oleander
- Foxglove
- Lilly-of-the-Valley
- Rhubarb
- Yew
- Mayapple
- Nightshade
- List of Poisonous Plant species
- Index of Poisonous Plants
- Plant Defenses Activity for Middle/High School
Key Concepts
Structures and Functions, Identification
Questions
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Posted by Leasen Oste on March 09, 2006 at 03:37 PM
Q: If the Wild Parsnip uses it's juice as a defense mechanism against humans by giving us a wicked sun burn, does this work on animals as well? What about animals with fur or scales?
A: I like your thinking on this but there is an assumption here that needs to be cleared up. Although we do get a really bad "sun burn" from this plant, it is most likely NOT a defense against humans but some other group of animals. The chemicals that help protect the Wild Parsnip are most likely useful to keep insects from feeding on it and we just happen to be especially suceptible to this combination. Since most mammals have a thick coat of fur and lizards have scales, it's unlikely that these chemicals would get on the skin of wild animals and cause this burn. My guess, and it's only a guess, however is that for many animals, if one smeared this chemical on a mouse's or deer's bare skin, for example, and then exposed this to the sun, one would see the same kind of damage as we get on their skin. Of course, the only way to know would be to try this out. Many kinds of plants have chemicals that help them avoid being eaten but just because humans are affected by these chemicals doesn't mean we're the target of this defense. I hope this helps. Thanks for asking.
Posted by Lyn Modic on August 22, 2005 at 08:44 AM
Q: I recently read about another related plant that causes the same problem that is moving into Ohio from Pennsylvania, but have lost the reference. Do you know what plant it is (common and scientific name)? Thank you.
A: There is another plant that's closely related to the Wild Parnsip that also produces phytophotodermatitus - it's Cow Parsnip (Heracleum lanatum). Cow Parsnip is a native parsnip in the parsley family and is present in Pennsylvania. There have also been unsubstantiated reports of Queen Anne's Lace having this property but I have never experienced this.
Thanks for asking.