A Field Guide to Poison Ivy, Poison Oak, and ... - Falcon Guides

Chapter 1
The Toxic Trio
Nature’s hostility to human interference is usually manifest
on a large scale, in such phenomena as global warming
and ozone-layer deterioration. These retributions
affect all living things. But the revenge wrought by poison
ivy, poison oak, and poison sumac is reserved exclusively
for the human inhabitants of planet Earth. Bears, birds,
and other wild creatures eat the berries and sleep among
the leaves with no ill effects.
The most common ill effect suffered by humans is a
dermatitis caused by contact with the plants’ oils. Rashes
and blisters erupt on the skin, sometimes oozing and weeping,
and always causing a pernicious itch. Less common
and more dangerous is contact with the smoke of burning
poison ivy, oak, or sumac plants or their parts. The oil that
causes the allergic reaction is carried in smoke and can
land on skin and in eyes and ears and can even be inhaled,
causing serious lung problems.
In North America, poison ivy and poison oak grow
happily from Mexico to Nova Scotia, except in the desert
areas of the southwestern United States. Their growth
requirements are simple. They prefer an elevation under
4,000 feet. They prefer sunshine but will do without. They
favor drier soils but tolerate moisture. They love ground
that has been disturbed and multiply freely on road
embankments and along forest trails. They spread happily
in city parks, such as Central Park in New York City, and in
suburban backyards.
Although poison ivy, oak, and sumac are essentially the
same plant, poison ivy resides in the eastern, midwestern,