Nature Bulletin No. 26 August 4, 1945
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Supt. of Conservation
It is blackberry time. Persons wandering through the woods should
learn to recognize and avoid poison ivy. It is a pernicious and frequent
vine along fences, roadsides and hedgerows; it grows in large patches of
erect plants in the deep woods, spreading by means of many
underground runners; and it climbs trees, clinging to the bark with
countless aerial rootlets. After the war we expect to eradicate large
areas of poison ivy, particularly in picnic centers and along the trails,
utilizing some of the new selective weedkillers that have been
developed. Poison ivy should not be confused with the harmless
Virginia Creeper, or Woodbine, which has five leaves coarsely toothed
all around their edges.
Poison ivy has three leaves. These are extremely variable in size, shape,
texture and color, sometimes more than a foot long, but normally from
2 to 6 inches long, from light to dark green in color, with smooth edges.
In May and June it has clusters of small greenish flowers; in late
summer and fall it bears little clusters of white or pale green berries.
The leaves, stems and fruit contain a non-volatile, poisonous oil known
as toxicodendrol. When this oil comes in contact with the skin it
produces a severe irritation and inflammation on most persons. Some
people are immune, and some are only slightly affected, but most
people -- particularly children -- are very susceptible to ivy poisoning.
The plant is dangerous the year round.
Some protection can be obtained by rubbing the legs, face, arms and
hands with a pasty lather of strong, brown laundry soap, allowed to dry
on the skin. As soon as possible after contact with poison ivy, wash the
exposed skin with this same soap and rinse thoroughly. Some
authorities also recommend alcohol, gasoline or baking soda. If a rash
appears, see your doctor immediately.
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Update: June 2012