The Three Poisons

Horticulture Chair Kevin Tepas recently presented the following information to the Club and we thought you all might like to have it on hand as you go about your fall raking, pruning and weeding.

POISON IVY (Toxicodendron radicans), POISON OAK (Toxicodendron pubescens) and POISON SUMAC (Toxicodendron vernix)]

  • All parts (leaves, branches, stems and roots) of all plants are toxic, containing the irritant, urushiol. This irritant can be transferred directly by physical contact with any of the parts of the plant. Itt can also be transferred indirectly, meaning you do not have to have physical contact with the plant. Your pet can give you a dose from its fur and so can the clothing while gardening if a part that touched the plant later touches your skin.
  • There are certain soap products that are designed to help remove urushiol from the skin. Tecnu™ is reported to be effective. Because of the tenacity of urushiol, affected clothing (by itself) should be laundered 2x.
  • It is critically important that you NEVER BURN ANY OF THESE PLANTS. Burning them transforms the urushiol into a gaseous state and if this is inhaled a potentially life-threatening medical emergency will result.

The purpose of this offering is to help you identify the poisonous plants. It was necessary however to omit the photographs that were in the original handout. Please be sure to visit to review images and to learn additional information about these plants.

Please also remember the default rule: Leaves of three, let it be…

Poison Ivy: (plentiful in this area)

  • Always has a longer stem on the center leaf (more correctly “leaflet”) than the stems on than the 2 “side” leaflets.
  • Always has pointed leaflets (unless the points have been removed by some animal or event)
  • Can look like an individual small plant or a larger shrub. It is also commonly a vine. When it grows up a tree it is “hairy” and has branches that grow off the vine at a 90° angle
  • Can have different leaflet shapes (but always pointed at the apex), making leaflet shape an unreliable ID factor
  • Can have different leaflet coloration, making leaflet shape an unreliable ID factor

Poison Sumac: (present locally though not as common as Poison Ivy)

  • Leaflet have smooth edges (i.e. “entire” margins) [The leaflets of other Sumacs almost always have some “teeth” on all or part of the leaflet.]
  • Berries are WHITE – Bark is smooth (not fuzzy) and has numerous visible lenticels

Atlantic Poison Oak: (not common locally but included anyway)

  • Looks almost identical to poison ivy. (e.g. always “leaves of three”)
  • Has leaves which grow in “alternate” arrangement (each consisting of 3 leaflets)
  • Never has thorns
  • Never has serrated (“toothed”) edges

Don’t forget to visit for photographs and for more information.