Poison Ivy, Poison Sumac, and Poison Oak Identification

Identify the Enemy Through Pictures, Descriptions

Poison ivy (image) has red leaves in spring. The weed looks different as year progresses.
Poison ivy in spring. David Beaulieu

"Leaves of 3, let them be." This rhyme pertains both to poison ivy identification (picture) and poison oak identification. The rhyme does not, however, pertain to poison sumac identification (i.e., the shrub, Rhus vernix; see my pictures). But people are far more likely to come into contact with the other two members of the triad than with Rhus vernix (there is also a non-poison sumac). All three are indigenous to North America.

In the U.S., poison ivy (Rhus radicans) grows everywhere but on the West Coast, while another vine (sometimes shrub), poison oak (Rhus diversilobum) grows primarily on the West Coast. In plant taxonomy, all three are sometimes classified as Toxicodendron rather than Rhus ("Toxicodendron" is from the Greek and literally means "poison tree"). Below, I speak mainly of Rhus radicans, but most of the facts related here also pertain to poison oak. For pictures of poison oak, see "Poison Oak Pictures" in the sidebar near the bottom of the page. I also offer information on how to get rid of poison oak.

The trademark grouping of three leaflets on Rhus radicans mentioned earlier assumes a reddish tinge when the leaves first come out in the spring, but the leaves turn green in the summer. Although the color (white) of its berries is often mentioned as a method of poison ivy identification, it is not as reliable as is identification by leaf.

The berries, after all, are produced only at the end of the growing season; knowing about the berries would do you little good when attempting identification in the spring. Incidentally, poison oak and poison sumac also have white berries. The non-poisonous varieties of sumac have red berries.

Picture, Description of a Plant That "Mimics" Rhus radicans

In the eastern U.S. another wild vine flourishes that is often mistaken for Rhus radicans -- Virginia creeper (Parthenocissus quinquefolia).

I provide a picture of Virginia creeper, elsewhere; it is also included in my "Pictures of Poison Ivy" gallery. But Virginia creeper more often has five leaves to a branch rather than three; and its leaves are more toothed than are the leaves on Rhus radicans. The fall foliage of this vigorous grower is truly spectacular.

While Virginia creeper vines do not contain urushiol oil, the compound that makes Rhus radicans toxic, you may need to shun contact with Virginia creeper, too. It turns out that the Virginia creeper's sap contains oxalate crystals, which can be toxic to some people. If you're unsure as to whether you're one of those people, don't touch Virginia creepers, since the result of contact could be a skin rash.

Like Virginia creeper, the fall foliage of Rhus radicans is surprisingly spectacular (for a poison ivy picture displaying fall foliage, see above right and also Page 3). One is tempted to ask, How can something that has caused so much suffering be so beautiful? The green summer color of the plant's leaves yields to brilliant fall foliage in red, yellow or orange. Their autumn brilliance is due to the anthocyanin pigments characteristic of the plant family to which they belong, namely, the cashew family (Anacardiaceae).

But if you're reading this article while plagued with the itching that the plant brings, you'll be much more interested in hearing some treatment tips than about how pretty the plant looks in the fall. And treating poison ivy rash is the subject of Page 2....

Now that we've identified poison ivy on Page 1, let's consider the matter of treating poison ivy rash. When we speak of a cure or treatment for this rash, we generally mean relief from its symptoms. Once the symptoms occur (itchy bumps on your skin), relief is the only remedy we seek -- before we scratch ourselves to death.

Different people find different degrees of relief by treating poison ivy rash with over-the-counter remedies, such as hydrocortisones.

Despite its inclusion in the classic rock song, "Poison Ivy," even Calamine lotion has its limitations as a treatment.

Some people have such a severe reaction to poison ivy that they need to visit a physician and get a shot. It usually takes about two weeks to get rid of poison ivy rash. For a home remedy, try applying the crushed leaves of jewelweed (Impatiens capensis). For a picture of jewelweed, see the photo above, on your right. The beauty of this home remedy is that jewelweed is a common weed in damp areas. This "treatment" may very well be growing right in your own backyard.

But there is another kind of treatment of poison ivy rash: namely, prevention. If you realize you've just come into contact with poison ivy, apply rubbing alcohol to the infected area and/or rinse with water (any water).

So what makes poison ivy (and poison oak and poison sumac, too)...well, poisonous? The answer is urushiol, which is the sap that runs through all parts of the plant.

Grazing against poison ivy with any exposed part of your body is all that it takes to release this poison. Complicating matters further, contact with poison ivy does not even have to be direct for you to contract the rash. For instance, if your dog runs through some poison ivy, then you stroke your dog's fur with your hand, you could come into contact with the sap and develop a rash.

Likewise, if someone else had been working in a poison ivy-infested area with gloves, then you came along and touched those contaminated gloves, you could get the rash.

So if the poison is spread that easily, poison ivy must be contagious, right? Wrong. It's only the urushiol that puts you at risk. Scratching your bumps doesn't cause the poison ivy to spread to other areas of your body. Nor will you contract the rash just by touching somebody else's rash bumps. Once the bumps are present, the damage that the urushiol can inflict has already been inflicted.

Now that you know how easy it is to contract the poison ivy itch, what you probably really want to know is how to get rid of poison ivy growing on your landscape. And that is the subject of Page 3....

On Page 2 we discussed how to get rid of the rash caused by poison ivy. Now it's time to consider various methods to get rid of poison ivy plants, themselves, where they grow in your yard. The first question to ask is how to remove poison ivy safely.

Indeed, a word caution is in order, before discussing any actions to be taken to get rid of poison ivy in your landscape. When approaching the itchy weed to engage it in battle, try to have as little of your skin exposed as possible, since it is through physical contact with poison ivy (all parts of it, including the roots) that the rash is contracted.

At the very least, this means wearing gloves, long-sleeved shirt and full-length pants. Secondly, understand that any of the removal methods discussed below may have to be implemented more than once to achieve complete success.

One organic method used to get rid of poison ivy is to pull it out by the roots. The roots must be disposed of; do not burn! Inhaling fumes from burning poison ivy causes far greater health problems than just the rash caused by skin contact. Another natural removal method is smothering. Smothering entails cutting the plants back close to the ground, then placing newspapers, cardboard, old carpeting, tarps, mulch or some other covering on top. However, be aware that, even after you kill poison ivy plants, they remain toxic. So be careful in disposing of the roots of the dead vines after pulling back the smothering agent (even if you've waited for years).

Herbicides can also be used to get rid of poison ivy.

Roundup spray is a popular but controversial glyphosate-based herbicide used to kill it. Another widely-available herbicide is Ortho Brush-B-Gon, which is triclopyr-based. These products will kill a great variety of woody plants, making them effective not only in getting rid of poison ivy, but also another nuisance vine: Oriental bittersweet.

But they will kill many other plants, too, so don't use them near specimens you wish to keep. If you choose to apply these herbicides by spraying, here's what to do:

  • You'll need a pressurized tank sprayer; mix the product with water, according to directions.
  • Apply when the poison ivy is fully leafed out.
  • Pick a day with little or no wind for spraying. Also, check your forecast: don't spray if rain is predicted at any time within the next 24 hours.
  • For poison ivy plants growing on the ground or on a wall, heavily spray the leaves and vines. Older plants have large hairy vines. Remember this fact to identify poison ivy in winter, when no foliage is present (rendering the "leaves of three, let it be" rhyme useless).
  • For poison ivy climbing up a tree, you may wish to "paint" the herbicide on, so as to preclude damaging the tree with a stray mist from your sprayer.

Please consult eradication of poison ivy and oak for more information on how to get rid of poison ivy.