Nature Bulletin No. 26   August 4, 1945
Forest Preserve District of Cook County
Clayton F. Smith, President
Roberts Mann, Supt. of Conservation

****:POISON IVY

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.