“Leaves of three, let it be” is how the saying goes. While poison ivy has compound leaves of three leaflets (and the whole plant contains urushiol oil that causes an itchy rash in most people), there are many other plants with three leaflets that you can get to know more closely.
Begin by developing a search image of poison ivy.
Poison ivy has a woody stem with usually short, unbranched shoots less than 2’ tall (it’s uncommon to grow as a vine in our region).
Poison ivy’s three leaflets together form one leaf. The leaflets are arranged in a T-shape; the middle leaflet has a longer petiole (leaf stem) and the side two leaflets have shorter petioles. Most poison ivy leaflets have some lobing on the edges (though some leaflets show none). Usually the middle leaflet shows symmetrical lobes on both sides, while the side leaflets have asymmetrical lobes with deeper lobes on the outer edge.
Now for a challenge! Can you spot the poison ivy and the three-leaflet non-poison ivy plant in the photos below?
Poison ivy in the red circle. Dwarf raspberry in the purple circle with regularly toothed leaflet edges.
Poison ivy in the red circle. Pointed-leaved tick-trefoil in the purple circle with smooth leaflet edges and larger center leaflet.
Poison ivy in the red circles – note how the young poison ivy leaves in the smaller red circle are more reddish than the older leaves. American hog-peanut in the purple circle with smooth-edged egg-shaped leaflets. Wild strawberries in the yellow circle with coarsely toothed leaflet edges.
Poison ivy in the red circle. Jack-in-the-pulpit in the purple circle with three smooth-edged broadly oval leaflets that have a border of a continuous vein around the edge.
Poison ivy in the red circle. Wild sarsaparilla in the purple circle with fine teeth along the leaflet edges. Wild sarsaparilla usually has five leaflets per leaf, but can also have three.