Tuesday, February 26, 2013

Leaves of three, let it be... What about leaves of five?

At some point in their life, almost everyone who has ever ventured out into the woods in Mid-Michigan has heard the phrase "Leaves of three, let it be." as a warning to avoid poison ivy.  Oddly enough this phrase causes more confusion than it solves.  I have seen people, both children and adults, avoid such plants as Wild Strawberry, Raspberry, Trillium, Box Elder, etc. because they were afraid that the plant was Poison Ivy.

The list of plants that I have see people confuse for poison ivy includes...


Blue Cohosh

Broad-leafed Toothwort

Jack-in-the pulpit
 
Large-flowered Trillium

Red Baneberry

Wild Strawberry
In all fairness, the majority of plants that people misidentify as Poison Ivy are young plants that lack flowers.  The idea of three leaves is so ingrained in many people that they assume any plant with three leaves to be poison ivy.

Another thing that confuses people about Poison Ivy is the fact that it can appear in multiple forms depending on species.  Western Poison Ivy (Toxicodendron rydbergii) is a can be a short groundcover less than 6 inches tall or a shrub from 1 to 4 foot tall.  Eastern Poison Ivy (Toxicodendron radicans) is a climbing vine. These vines can be thin in young plants or they can be 3 inches thick twining around a tree with no leaves visible for the first 20 feet.  The vines of Eastern Poison Ivy are often hairy.

If there is one plant that people seem to confuse the most with Poison Ivy it is this one...

Virginia Creeper - fall colors
Virginia Creeper (Parthenocissus quinquefolia), like Poison Ivy, is a climbing vine, but that is where the similarities end.  While Poison Ivy has leaves in clusters of three, the compound leaves on the Virginia Creeper are typically in five parts (occasionally three or seven parts).  Poison Ivy leaves are smooth edged or have a few teeth, Virginia Creeper leaves are coarsely toothed around their entire margin.  Poison Ivy leaves are a glossy mid- to dark-tones green; Virginia Creeper leaves are dark green above and light green below.  Both Poison Ivy and Virginia Creeper produce  berries, white on the Poison Ivy and Blue-black on Virginia Creeper.  Virginia Creeper is not an ivy, but many people refer to it as Five-leafed Ivy adding to the confusion.

Now that you know what about plants that are not Poison Ivy, what does Poison Ivy actually look like?  Here is an example of the Eastern form in the fall. 

Eastern Poison Ivy vine climbing a tree

A close-up showing the clusters of three leaves
With just a little practice, Poison Ivy can be relatively easy to identify if you know what to look for.

UPDATE:

Here are some links to other posts that I have written about poison ivy since this one

8 comments:

  1. my yard is filled with wild strawberry, they grow close to the ground, although they sometimes get mowed. A tree now has a vine beginning to climb, with larger leaves that match the strawberry leaves, but i'm afraid this is poison ivy. How do I tell the difference? Thank you!

    ReplyDelete
    Replies
    1. If the leaves of the climbing vine are coarsely toothed like those of the Wild Strawberry then it is not Poison Ivy. Poison Ivy leaves are smooth edged or have a few teeth. Another thing to check is the arrangement of the leaves. Poison Ivy leaves always grow in a cluster of three, if the leaves are in a cluster of five it is probably Virginia Creeper. Look at the last three pictures above to see the difference between the Virginia Creeper and Poison Ivy leaves. If it ends up being Poison Ivy there are a number of herbicides that can be applied that will kill it - talk to someone at a local gardening or farm center to find out which.

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  2. Hello,
    Can you tell me what the back of wild strawberry leaves look like? Are they white?

    Also what do the back of poison ivy leaves look like?

    Thank-you
    Helen

    ReplyDelete
    Replies
    1. Helen,

      I just wrote another post about Poison Ivy with pics of the backs of leaves. Hope this helps.

      http://midmichigannatureandscience.blogspot.com/2013/06/leaves-of-three-revisited.html

      -Mike

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  3. Hi Mike,
    Thank-you for the picture showing the underside of the poison-ivy leaf. I was mistaken when I thought it might be Wild Strawberry as now I think it is Wild Raspberry.

    The plant I am trying to id has thorns on the stem and is whitish green and the underside of the leaves are clearly white. I would post a picture but don't know how to do so.

    Regards,
    Helen

    ReplyDelete
    Replies
    1. Sounds like either raspberry or blackberry to me.

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  4. Hello Mike,

    Thanks for the information! My family has been avoiding Virginia Creeper for generations, because we thought it was poison ivy. However, I would like to know what climate poison ivy grows best in, so I can be more prepared.

    Raina

    ReplyDelete
    Replies
    1. Poison Ivy grows in just about any type of upland habitat - woodlands, open fields, etc. It doesn't do as well in wetlands but will still grow in places where the soil is not too wet.

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