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  Poison Ivy
Poison ivy packs a powerful punch.

W
Place your cursor over the slideshow for captions.
atch out! It could be a very itchy and scratchy summer. No, we're not talking about the cartoon cat and mouse characters from The Simpsons. We're talking about that three-leaf monster, poison ivy. Scientists think poison ivy is getting bigger and meaner—and spreading like a bad rash.

The Pretty Weed With the Nasty Touch
Without thorns or prickers, poison ivy looks like an innocent plant. It often grows near streams, rivers, and lakes, as well as by the edges of roads and forests. Various species of it can found across most of the United States. The plant has three leaves on each stem. Those leaves are usually green, but may turn red, yellow, or orange in the fall.

Touching any part of the weed —the leaves, stems, or roots—spreads an oily substance called urushiol on the skin. (Poison oak and poison sumac are other plants that produce urushiol.) That substance causes most people to break out in an itchy rash that can be very irritating, and sometimes dangerous.

Something's in the Air
Poison ivy has always been a summertime pest. But now scientists think it might be packing more heat. The reason is carbon dioxide (C02). This invisible gas is one of the four things plants need to live, along with sunlight, water, and nutrients. Carbon dioxide is released into the air when people and animals breathe out. It is also produced when people burn fuels such as coal, oil, and gas. C02 is a normal part of Earth's atmosphere. However, too much C02 in the air can cause serious problems, such as changing normal weather patterns.

Scientists have studied the effects of high levels of C02 on poison ivy. Poison ivy plants exposed to more C02 did "grow more, have more leaves," and make more powerful urushiol, says Lewis Ziska, a research scientist with the U.S. Department of Agriculture. That finding suggests that as the amount of C02 in the air increases, poison ivy becomes more dangerous. The amount of C02 has already increased. Today's air contains about 22 percent more C02 than air in the 1950s did, Ziska points out.

Researchers are trying to put that bad news to good use, says Ziska. They are trying to grow rice plants that thrive at higher C02 levels "and put more food on people's plates."
Think About It!
  • Poison_IvyWhy might today's air have more carbon dioxide in it than it did in the 1950s?
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    Go Out and Play!
    None of this means that armies of giant poison ivy plants are waiting to attack you. Nor does it mean you should hide indoors during the summer. Just learn to avoid the "three-leafed monster" and stay safe!

    Stay Safe
    What can you do to avoid an itchy rash? Here are some tips:
  • Learn what poisonous plants look like. (The Web sites below have pictures.)
  • Remember the saying "Leaves of three, let it be." That applies to poison ivy and poison oak; but poison sumac has at least seven leaves.
  • Don't touch poisonous plants, not even in the winter or if they're dead; they can still make you itch.
  • If you do touch poison ivy, rinse your skin immediately with rubbing alcohol and cool water. Then wash with soap and water.
  • Products such as calamine lotion can treat the rash. If the rash is really bad, or is on your face, see a doctor.
  • Scratching a rash won't spread it, but can cause an infection.
  • If you have a dog, don't let it go near poison ivy. The itchy substance can get on its fur, and then on your hands when you pet the dog.

    • Did You Know?
    Poison ivy causes itchy rashes in humans and some kinds of apes, but doesn't harm other animals.

    Burning poison ivy is a bad idea: People can breathe in the urushiol fumes and harm their lungs.
    Check out this Poison Ivy word search!


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