How to Identify Poison Ivy, Oak, Sumac and Hogweed

Apparently this summer of 2013 has seen an increase in poison ivy, oak and sumac plants in the Ottawa area. I don’t know the reason for this, perhaps it is because of all the rain we have had. These plants are cropping up along nature trails, golf courses and even in small residential gardens, creating misery for anyone that comes into contact with them.

The first picture shows you what poison ivy, oak and sumac plants look like.   The next three pictures are of giant hogweed; flower, leaves and stem/stalk respectively.    Hogweed looks something like Queen Anne’s Lace, a common wildflower found along Ontario roadways, except Hogweed flowers are rounder and larger.  This plant can grow up to 15 feet tall with the leaves reaching up to 5 feet in size.  The stems are green with purple spots and white hairs.

poison plantshogweedhogweed leaveshogweed stalk

Poison ivy and oak can grow as a plant, shrub or vine.  Poison sumac only grows as a shrub.  They  all have an oil called urushiol on all parts of the plants, including the roots.  The urushiol is easily transferred to objects that come into contact with the plants, including skin, gardening tools, pets, camping equipment, golf clubs etc.  An allergic reaction to the uroshiol causes a skin rash that can develop anywhere from hours to days later.  The rash then develops into oozing blisters with streaks or patches where the contact with the oil occurred.   This reaction usually lasts from five to 12 days, but can extend to thirty days in a severe case.  The rash is not contagious, as the blisters do not contain the uroshiol.  You can, however, continue to be exposed if the object the oil contacted is not cleaned well.  You can also inhale the oil from the smoke if the plant parts are burned, causing severe reactions in the throat, nose and lungs.

Hogweed causes a much more severe reaction, but the reaction is not caused by simply brushing against the plant as with poison ivy, oak or sumac.  The stems, leaves and roots of hogweed contain a clear, liquid sap which leaks from the plant parts only when they are broken.  When the sap comes into contact with skin and the skin is exposed to sun, a reaction occurs, causing a painful, burning  blistering rash with purple/black scars.  This reaction can last for years.

Please make sure you know how to identify these poisonous plants, and steer clear of them!