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  5. Leaves of three – identifying Poison Ivy

Leaves of three – identifying Poison Ivy

“Leaves of three? Let it be!” Even though it can be challenging, learning to identify Poison Ivy could save you and the people around you a LOT of discomfort.

Jennifer Doubt, the Museum’s Curator of Botany, explains that many species (including Trilliums, Strawberries, Clover …) have their leaves or leaflets arranged in threes. On top of that, there is a lot of variation in the forms Poison Ivy can take. It can be a tiny shoot or a huge vine climbing up the side of a tree. The edges of the leaves can be smooth or wavy or toothed. No wonder so many people get tricked every summer!

When should you be EXTRA suspicious?

  • The middle leaflet in each group of three normally has a longer stalk than the two leaflets on either side.
  • The leaflets are usually pointed at their tips rather than blunt (strawberries and clover have three leaflets, but they are blunt or rounded at their tips).
  • Although they can be notched, the leaflet margins do not have tiny, even, sharp saw-like teeth, the way strawberries and raspberries do, for example. 
  • Most leaves really do have three leaflets. Manitoba Maple looks an awful lot like Poison Ivy when it is young, but as it grows older, you will see more and more leaves with 5 or more leaflets (plus, eventually, it will become a tree. Poison Ivy can form very tall vines up the sides of trees, but doesn’t grow into a tree on its own.)
  • In the fall, Poison Ivy often has white berries and can turn red like some trees do (and even then, it can still make you itch!).

Enjoy exploring nature and watch your step! 

 

© Canadian Museum of Nature

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Manitoba Maple looks a lot like Poison Ivy when it’s young.

© Canadian Museum of Nature

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The youngest leaves of this Manitoba Maple have more than three leaflets.

© Canadian Museum of Nature

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Woodland Strawberry / Fragaria vesca L.

 

© Canadian Museum of Nature

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Poison Ivy

© Canadian Museum of Nature

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A Poison Ivy specimen from the Museum’s National Herbarium of Canada, collected in fall 1922 in Aylmer, Quebec.