Poison ivy Toxicodendron radicans
IDENTIFICATION — Just about every gardener’s least favorite weed! Not only does poison ivy grow and spread rapidly, but it gives many people an itchy, sometimes painful, rash. This woody weed can have an upright form up to 7 ft. tall or appear as a climbing vine, hanging on to trees or fences with dark aerial roots.
The three leaflets, which are sometimes shiny, have a wavy edge and a reddish cast and stem. Insignificant green-white flowers appear in late spring, followed by fruit that ripens about the same time the leaves turn red in fall.
FAVORITE CONDITIONS — Poison ivy prefers moist, rich soil in full sun to part shade. You can find it along roadsides, in wooded, moist or wet areas.
CONTROL — To pull or cut back the plant, be careful to keep urushiol, the sticky oil that is present in all parts of the plant, off your skin. Wear long pants, long sleeves and double gloves. If you don’t want to handle it, spray the plant with a systemic herbicide like Roundup®, but it’ll take time and several applications to eradicate it. You can also dab or spray the cut ends of the vine with a systemic brush killer (again, a herbicide that contains triclopyr is best.)
LOOKALIKES — Another sneaky thing about poison ivy: It has some lookalikes. You’ve probably heard the old saying, “Leaves of three, let it be.” That’s good advice — poison ivy doesn’t really stand out in a crowd, but it always has three leaflets on each leaf.
However, small box elder (Acer negundo) seedlings look similar, and they tend to grow in the same places you’ll find poison ivy — along the fence, behind the garage, and other places where you may not do a lot of cultivating. The clues? Boxelder stems often have a grayish “bloom” on them.
Another lookalike is Boston ivy (Parthenocissus tricuspidata), especially small, new growth. Unfortunately, it has a red stem, just like poison ivy, so it’s a little harder to tell apart. Usually the leaf edges are a little more jagged, and the leaves are slightly smaller. But when in doubt, it’s best to be careful!