One thing we find frustrating when reading articles on the topic
of poison ivy and poison oak is when this line gets regurgitated
over and over: "poison ivy and poison oak have three leaves, but
can sometimes have as many as five to seven leaves". We’ve
seen over and over where this creates confusion and leads
people to misidentify 5 leafed vines (like Virginia Creeper)
as poison ivy.
To set the record straight, poison ivy and poison oak have 3 leaflets per leaf, which is where the phrase "Leaves of three,
let them be" comes from. They have a 3 leaflet pattern very
nearly 100% of the time.
It isextremely rareto find a poison ivy or oak plant that has more
than 3 leaflets per leaf. Like one in 100 Billion.
Below are some examples of these exceedingly isolated cases
of extra poison ivy leaflets:
5 leafed poison ivy
found in Lincoln, MA
5 leafed poison ivy
found in Concord, MA
Photo courtesy of Helaine Hughes,
The Poison Ivy Removal Company
Photo courtesy of Jim Byler,
The Poison Ivy Guy
5 leafed poison ivy
found in Philadelphia, PA
5 leafed poison ivy
found in Des Moines, IA
Photo courtesy of Umar Mycka,
Poison Ivy Horticulturist
Photo courtesy of Dan Boelman,
Zanfel Laboratories
All of the above were positively identified as poison ivy by
professional poison ivy removal service providers, and some
were also verified by using a See-Leaf urushiol detection wipe.(www.sealeaf.com).
The Plants With 5 Leaves
There is a very common group of plants which are woody
vines with five leaves. These members of the Parthenocissus
genus include the plant species commonly called Virginia Creeper, Woodbine and others. These plants are frequently mistaken for poison ivy, even though they have five leaflets per leaf (whereas poison ivy has three). The ranges of these five leafed plants cover the US, and most of North America. Unlike poison ivy, these plants are not known for producing allergic skin reactions.
Virginia Creeper
Woodbine
Photo courtesy of Missouri Botanical Garden
Photo courtesy of Peter Dziuk