Poison Ivy (Toxicodendron Radicans)

Features and Characteristics

Toxicodendron radicans, commonly called poison ivy, is the ultimate weed that no one wants. “Leaflets three, let it be.” It is native throughout the United States and much of southern Canada in a large variety of locations including dry or wet woodlands, thickets, valleys, clearings, fencerows, roadsides and waste ground. It is found in every county in the State of Missouri. It primarily appears as a bushy, erect or trailing shrub or as a woody climbing vine. Climbing vines have aerial rootlets. All parts of the plant contain a toxic plant oil called urushiol which can cause significant and long-lasting skin irritations (allergic dermatitis) in most human beings. Infection can occur from direct contact with the plant, indirect contact (e.g., dog, rake or shoes) or from breathing smoke from a fire of plant material. Some humans seem to be immune. Compound green leaves are alternate, but can be quite variable in characteristics. Each leaf has a stem with three leaflets that are smooth or toothed, rounded or pointed and glossy or dull. Leaflets are glabrous to hairy beneath. Leaves turn red-yellow in fall. Greenish-white flowers bloom May to July. Waxy, creamy-white to yellowish-white berries (drupes) in axillary clusters ripen in late summer and persist into winter. Some birds feed on the fruits. Toxicodendron radicans is synonymous with Rhus radicans.

Genus name means poison tree.

Specific epithet means with rooting stems.