Poison ivy, oak, and sumac are found throughout the
continental United States. In general, poison ivy grows east of the Rocky
Mountains, poison oak west of the Rocky Mountains, and poison sumac in the
southeastern United States.
The plants may look different depending on the season and the area
where they are growing. But all of these plants have small white, tan, cream,
or yellow berries in the fall. Their berries can help distinguish them from
harmless but similar plants.
After the leaves have fallen off, these plants can sometimes be
identified by the black color on areas where the oil in the plant (urushiol)
has been exposed to air.
Poison ivy is found
everywhere in the United States except Alaska and Hawaii. It is most common in
the eastern and midwestern states. It is less common outside the United States,
but still found on every continent.
Usually has three broad, spoon-shaped leaves or
leaflets, but it can have more. The phrase, "Leaves of three? Let it be." may
help you remember what poison ivy looks like.
Grows as a
climbing vine or a low, spreading vine that sprawls through grass (more common
in eastern states) or as a shrub (more common in northern states, Canada, and
the Great Lakes region).
Often grows along rivers, lake fronts, and
Has bright red leaves and white or cream berries in
Poison oak is most common in the western United States,
although it is also found in eastern states. It rarely is found in midwestern
Has leaves that look like oak leaves, usually
three leaflets but sometimes up to seven on each leaf group.
Grows as a
vine or a shrub.
Poison sumac is much less
common than poison ivy or poison oak. It is found in wooded, swampy areas, such
as Florida and parts of other southeastern states. It is also found in wet,
wooded areas in the northern United States.
Has 7 to 13 leaflets on each leaf stem. The leaves
have smooth edges and pointed tips.
Grows as a shrub or small
Where they are not found
None of these plants grow well above
4000 ft (1219 m), so the higher
elevations in places such as the Rocky Mountains are relatively free of
None of these plants grow well in deserts, except along the
banks of rivers, streams, and ponds. But heavy rainfall can make a dormant
plant grow again, even in a desert.
Hawaii does not have any of
these plants, although other plants that cause a skin rash are found on the
islands. For example, mango trees grow in Hawaii, and the skin of mangoes
contains the same allergenic oil (urushiol) as these plants.
These plants do not grow in Alaska, and they are rarely
found in the rainforests of Washington state and Oregon.
How this information was developed to help you make better health decisions.