Poison Ivy

By William T. Hathaway

Poison Ivy (Rhus radicans)

Those of us with some knowledge of plants classify Poison Ivy as Rhus radicans — a high-climbing vine with many clinging roots, a vine that often spreads over extensive areas. Poison Oak, Rhus toxicodendron, is known to us as an erect, slender-stemmed plant with very few branches; the stems may become 2 meters tall. Both poison ivy and poison oak are extremely toxic.

It is interesting that some botanists consider poison ivy and poison oak to be the same species; that is, they are ecotypes. Ecotypes are a group or race, within a species, having unique physical characteristics generally adapted to particular environmental conditions. Guess what! If you plant seeds of poison ivy or poison oak in the same location, both seeds will produce the same plant, either poison ivy or poison oak.

Occasionally, poison ivy branches will reach out from tree trunks, appearing as tree branches with leaves. Young students in leaf-gathering studies have been fooled by this unlikely habit of poison ivy — much to subsequent dismay of the student.