Topics
- Introduction (0:00-0:20)
- Poison ivy (0:20-6:46)
- Spotted touch-me-not, aka jewelweed (6:46-12:54)
- Wildflowers (12:54-14:31)
- Butterflies (14:31-15:45)
- Conclusion (15:45-17:33)
Ir-rash-ional fears holding you back?
Most Minnesotans are familiar with the adage “Leaves of three, let it be.” For the 50% of us that react to the irritant, a childhood summer outdoors almost always included a rash or two. (Who’s accidentally left their towel in the wrong spot and ended up with a full-body rash?)
Fear of poison ivy can make people afraid to explore or attempt to eradicate every three-leaved plant in their area. However, iconic spring wildflowers like Jack-in-the-pulpit and trilliums also have “leaves of three,” along with the innocuous but ubiquitous hog peanuts. Overzealous culling of three-leaved plants is wasted effort and hard on the desirable plants.
The good news is, poison ivy is decently easy to identify and remove, and even if you inadvertently stray through a patch, you can still avoid getting a rash.
Edit/undo for skin irritants
Step one to learning to identify a poison ivy plant: examine from a distance. Unless you know for sure you’re one of the lucky people who doesn’t react, don’t go fondling the foliage, berries, bark, or roots!
If you do get exposed, you can simply rinse with water immediately. If you’re unable to do so, or aren’t sure if you’ve been exposed, the remedy is simple – wash within 2 hours using soap. This may not entirely prevent a reaction but will greatly reduce its severity.
Step one: look at the stem
The quickest way to rule out the “friendly” three-leaved plants is to take a careful look at the stem. If the stem is brown and woody, you’ve got poison ivy – if not, you’re dealing with a friendly plant. (Use a stick to move the leaves out of the way if the stem isn’t visible.)
Remember: Woody stems would give you a rash!
Double check it actually is three-leaved: woodbine (also known as Virginia creeper) has a similar stem type, but has 5 leaves.
If you don’t want to bend down far enough to look at the stem, you can also look at the leaves, though they’re more variable and harder to distinguish.
Step two: leaf it alone
If you prefer to identify by leaf, look for three key asymmetries. In order of reliability, they are:
- One of the “leaves of three” has a longer stem than the others
- Individual leaves are lopsided, with one side larger than the other
- Individual leaves have more lobes on one edge of the leaf than the other
This system is less reliable, because poison ivy leaves are extremely variable. Individual poison ivy plants can vary in how asymmetrical they are, and some lack lobes entirely.
At least the first rule is reliable! If mental images help you, I always picture the structure of poison ivy leaves as two arms and a head.
Our friendly spring wildflowers trillium and Jack-in-the-pulpit don’t have this shape: their three leaves emerge in a single whorl, are always smooth-edged, and their stems are soft and non-woody.
Poison ivy and hog peanuts both have the two-arms-and-a-head shape, but poison ivy leaves are larger, thicker, and have more prominent veins running through them. Hog peanut leaves are thinner, more delicate, and always have smooth edges. (Also, the stem is not woody,)
Something doesn't match up
If you’re still not sure, take a good look at the individual leaves. Poison ivy leaves are lopsided, with one half of the leaf larger than the other. (Hypothetically, if you folded the leaf in half along the central vein, the two sides wouldn’t match.)
Often, one side will have more lobes/teeth on the edge of the leaf. (Some poison ivy leaves have no lobes, though – so tricky.)
Get out and explore!
Walk and weed carefully but confidently, my friends – enjoy a rash-free summer!
That does it for this week! For more phenology, subscribe to our Season Watch Newsletter or visit the Season Watch Facebook page.
Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).
