There are several plants that grow in Ontario that can cause serious injury if touched or ingested. Property owners, in particular, should take care that none of these plants grow on their property where they may injure someone coming onto the premises. These harmful or noxious plants are generally found in public parks, conservation areas and wild areas, often where people walk, bike and play, and can result in serious injury to an unassuming visitor. Five particularly dangerous plants that are found in Ontario, particularly in Southern Ontario, are wild parsnip, giant hogweed, poison ivy, wild hemlock and pokeweed.
In July 2015, an 11-year-old boy experienced a small scratch on his leg from a plant when he fell off his bike along a municipal trail north of Ajax. Within a few days, the entire back of his leg was covered in large red blisters, likely caused when he fell onto or touched wild parsnip that was growing along the trail. Wild parsnip is a pretty wildflower that has yellow blooms, but everyone should be wary of the noxious sap that can blister and leave scars. Wild parsnip makes skin hypersensitive to burning, and can even blind people.
Wild parsnip is not only dangerous to people, but also to dogs and other animals, and has been seen in many natural areas, including in the Durham Region. Some experts believe that heavy construction activity helps spread the seeds of this plant. Conservation authorities and other municipal organizations request that people report any infestations of wild parsnip or other invasive plants so that they can be mapped and dealt with. Experts suggest that construction companies properly clean their equipment before moving from site to site, or they may be responsible for the spread of these plants.
Giant hogweed is another dangerous plant that is very invasive and grows throughout Ontario. It has reddish purple stems that can reach 4-5 meters. Public health officials have identified giant hogweed as a ‘public health hazard’. Coming into contact with sap from the plant can cause painful blisters and third-degree burns when combined with sunlight. After suffering skin irritation from this plant, a person may continue to get blisters when exposed to sunlight, for as long as a decade after they were exposed. Like wild parsnip, giant hogweed can also cause permanent blindness and scarring.
After coming into contact with giant hogweed, wild parsnip or another noxious plant, a person should thoroughly wash the effected area with soap and cold water (as hot water tends to open the pores), and avoid exposure to sunlight for at least 48 hours. Effected persons should also see their doctor and report their sighting of the plant to the Ministry of Natural Resources or the authority responsible for the area where it was found. Giant hogweed is particularly common along river banks, but can also be found along trails and roadsides.
Poison ivy is a plant most familiar to Ontarians as potentially dangerous. Poison ivy can be recognized by its glossy green leaves, of which there are three leaves on each stalk. It is most commonly found along the edges of forests, in meadows and on trails. Contact with poison ivy, particularly when the leaves are broken, can cause a skin inflammation for most people who are exposed. The oil resin from the plant can also be transferred to the skin from our clothing, pet fur, shoes or anything else that comes into contact with it.
Spotted water hemlock contains cicutoxin, a toxic substance that attacks the central nervous system. Water hemlock is extremely dangerous and can result in coma and respiratory failure within 30 minutes to 8 hours. Symptoms of poisoning from this plan include extreme salivation, severe abdominal pain, violent convulsions and delirium. Water hemlock tends to grown in wet areas, including marches, swamps, river banks, ditches and wet meadows. Water hemlock can reach 2.2 meters in height and gets small, white flowers that have an inverted umbrella shape.
Pokeweed is another dangerous plant and poisonous to both humans and animals. Pokeweed poisoning can cause the following symptoms: blurred vision, sweating, weakness, vomiting, abdominal pains and unconsciousness. Pokeweed is most often found at the edges of woods, meadows and waste areas in Southwestern Ontario. It can be recognized by its large egg-shaped dark-green leaves and red stalk. It’s flowers appear white to green and it develops a fruit that is first green then deep purple or black.
It's a good idea to learn to recognize these five plants, particularly if you or your family enjoys walking and biking on community trails or wild areas. Also, teach your children not to pick or touch wild plants.