Poisonous to Touch Weed Series: Poison Sumac (Toxicodendron vernix)

Poison Sumac (Toxicodendron vernix) is a perennial shrub or small tree, native to eastern Canada as well as east-central and eastern United States. Like poison ivy and poison oak the leaves and berries of this plant contain urushiol (an oily mixture of organic chemical compounds); but the oil is said to be more concentrated in poison sumac. The Urushiol can cause a severe allergic reaction in sensitive … Continue reading Poisonous to Touch Weed Series: Poison Sumac (Toxicodendron vernix)

Poisonous to Touch Weed Series: Wild Parsnip (Pastinaca sativa)

Wild parsnip (Pastinaca sativa) aka poisonous parsnip is one of the phototoxic weeds we grow here in Canada. It is a non-native and as such is an aggressive and invasive species. It is the only one of the phototoxic weeds that has a yellow flower, the others bearing white umbels. It’s pinnately compound leaves are also quite different than the palmately compound leaves of cow … Continue reading Poisonous to Touch Weed Series: Wild Parsnip (Pastinaca sativa)

Poisonous to Touch Weed Series: Giant Hogweed (Heracleum mantegazzianum)

Giant hogweed (Heracleum mantegazzianum) is likely the largest and most dangerous to touch perennial weed in North America. In Ontario it commonly reaches heights of 3-4.5m but in other parts of the world it can reach heights of 5.5m (MacDonald F. and Anderson H. 2012). There are a few other Giant Hogweed species that are a bit smaller in size but Heracleum mantegazzianum is the … Continue reading Poisonous to Touch Weed Series: Giant Hogweed (Heracleum mantegazzianum)

Poisonous to Touch Weed Series: Poison Ivy (Toxicodendron radicans and Toxicodendron Rydbergii)

By: Kimberley Pacholko Eastern Poison Ivy, (Toxicodendron radicans) and Western Poison Ivy (Toxicodendron Rydbergii ) are important plants to learn how to identify for personal safety. Touching any part of this plant can cause a painful itchy rash with red swollen skin and painful blisters. I have had the miss fortune of being caught twice by this plant and can testify to how unpleasant the … Continue reading Poisonous to Touch Weed Series: Poison Ivy (Toxicodendron radicans and Toxicodendron Rydbergii)