Friday, July 29, 2011

Leaves of Three

By: Lacy Sellent, Writing Fellow at the Cable Natural History Museum

As a kid, there was one plant that my parents always warned me about—poison ivy.  It never looked all that bad to me.  For the most part the leaves were only about two or three inches long.  The plant didn’t even look sharp or prickly like a thistle.  Well, it didn’t take me long to learn to follow my parents advice—that when I saw “leaves of three,” I needed to “leave them be”.

All it takes is one little brush against your leg and within a few days you’ll break out in a nasty rash.  It will itch and may even ooze a bit.  Yeah, I know, it’s not very pleasant.  This is actually a type of allergic reaction.  It’s caused by urushiol, a type of oil made by the plant.  The leaves, the stem, and even the roots all have this pesky stuff on them.

On the bright side, if you realize you’ve come in contact with poison ivy you may be able to spare yourself from its not-so-nice side effects.  By washing your skin with alcohol—within ten minutes after touching it—you can still rid yourself of the oil.  Washing with water will also help.  If you are not able to wash your skin within ten minutes (or don’t realize that you’ve come across any poison ivy) then the oil is already soaked up into the skin.  At this point, it can no longer be washed off.  The main thing is to try to wash everything that touched the plant as soon as possible.  This includes your shoes and clothing. 

Your clothes can not absorb the urushiol in the same way that your skin can.  Because of this, the oil on your clothes can cause rashes for months after your first contact. Although many believe the rash itself is catchy, the rash is more likely to be spread through fabrics.  A shared pair of gardening gloves may be to blame for the spread of a rash from one person to another.    

Another good thing to know is that not everyone who touches poison ivy will break out in a rash.  But there’s a catch.  The more times you come in contact with poison ivy, the worse your reaction may become.  For example, the first time you touch poison ivy, you may not see a rash until over a week later (if you ever see one at all).  After a few more run-ins with poison ivy, you may start to see a rash in as little time as a day or two. 

What’s really creepy about poison ivy is that, according to Dr. Lewis Ziska (from the U.S. Department of Agriculture), it has begun to grow larger and more poisonous than ever before.  Poison ivy plants are now capable of growing twice the size today as they were back in 1901.  This is partially due to more carbon dioxide in the atmosphere.  Since carbon dioxide is what plants eat, poison ivy (among other nuisance plants, such as poison oak) is able to produce more food.  When combined with the results of logging (which opens up a forest—giving more light for the poison ivy to grow) and other land use activities, we could be creating the perfect environment for poison ivy.

On the flip side, poison ivy is a native plant to Wisconsin and, therefore, has its part to play in the Northwood’s environment.  Everything from bluebirds and robins to turkeys and crows either eat the berries of the poison ivy plant (which are present in late summer) or they use the plant as cover.  Even deer will munch on poison ivy, only they’ll mostly eat the leaves.  In some cases, people like having a bit of poison ivy around because then the deer eat that instead of their garden.

As you explore the woods this summer, keep in mind that nature can be fun and we also need to be aware of its dangers.  Now that you know more about poison ivy, get out there and enjoy your summer—just stay away from those leaves of three!

For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, The Joy of Birds: Feathers in Focus opened in May, 2011. Find us on the web at to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot,

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