Poison ivy is well known for the reactions most people have from handling or brushing against the plant, but despite its notoriety, many people also find it hard to recognize. To add to the confusion, there are mentions of poison oak and poison sumac.

Poison ivy is native to Kansas and prolific in woodlands and on roadsides. It also frequently pops up in landscapes and gardens. It is the only one of those three plants that warrants concern in the northeast portion of the state.

An old saying about poison ivy is “Leaves of three, let it be.” This refers to the clusters of leaflets, always borne in groups of three, that are a key identifying characteristic. The leaflets have a teardrop shape and are usually 3 to 4 inches long. Beyond that, describing them is tricky. The leaflets’ edges may be smooth, jagged, or have small irregular lobes. They also range in shades of green and, if damaged, may turn red or have red spots. In the fall, the leaflets turn a brilliant shade of red.

Poison ivy grows as a seemingly tender herbaceous plant, a small shrub, or as a vine. In landscapes and gardens, it is most likely to appear in herbaceous or vine form. Woodland areas and roadsides are more prone to shrubby poison ivy or thick, vigorous vines, since the plants are more likely to be left to grow in these areas.

The skin reaction to poison ivy is from contact with an oil found in the plant called urushiol. The oil is in all parts of the plant and is released when the plant is damaged. Walking through it or brushing against may be enough to release the oil. The oil also sticks to clothing, pet fur, tools, garden gloves, etc. Extreme care should be used when trying to remove poison ivy from an area or working in an area where poison ivy is growing.

Poison oak is not known to be in northeast Kansas. The USDA Plants Database, which provides information about distribution of various plant species in the United States, shows that poison oak has only been identified in Kansas in Chautauqua and Cherokee counties.

Poison oak produces leaflets in clusters of three similar to poison ivy. Poison oak leaflets are smaller and have lobes similar to white oak leaves. The oil in poison oak is the same as in poison ivy and produces the same reaction to those who are allergic to it.

Poison sumac is not known to grow in Kansas. It is native to the eastern and southeastern portions of the U.S. Each leaf comprises seven to 13 leaflets arranged along a stem like a feather. Leaflets are similar in size and shape to poison ivy. The plant also contains urushiol.

If you’re attempting to remove poison ivy, the course of action depends on the size of the infestation. Small plants may be pulled (wear rubber gloves and long sleeves) or dug out. Larger plants are best controlled by cutting the stems at ground level and treating stumps with a weed or brush killer.

If poison ivy contacts bare skin, wash the affected area with a special product labeled to remove urushiol (available in the first aid section of most stores) or use dishwashing detergent.

If poison ivy contacts clothing, carefully remove the clothing as soon as possible and launder it.

— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.