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Posted: September 20, 2019

Plants that sting and burn

What to be cautious of and how to identify dangerous plants

A recent post on an Elk Valley local’s Facebook page has gone viral after a dog developed a blistery rash following a routine walk near the Sparwood Ski Hill. The post pointed to Giant Hogweed, a well-known invasive plant species in North America.

After several attempts to locate the culprit plant, the East Kootenay Invasive Species Council (EKISC) is confident that Giant Hogweed was not the cause of the dog’s ailment.

“There are currently no confirmed locations of Giant Hogweed in the East Kootenay,” said Katie Reid, EKISC’s Operations Manager, “Both EKISC and our area contractor have been out to search several possible locations of the reported plant but have not seen any evidence of its existence in the area.” She added, “of the 1150 Giant Hogweed plants recorded in B.C. since 2005, 99% of the sites are found within 140 km of the coastline.  There have only been eight sites found outside of this area, and half of those were on private land.”

Jessie Paloposki, EKISC’s Education and Communication Manger explained: “Many people often misidentify and report Giant Hogweed as it looks extremely similar to a locally native species, Cow Parsnip.” She offers this resource that can help people better distinguish the plants.

Native to Europe and Asia, Giant Hogweed was introduced to North America as an ornamental plant in the early 1900s. It is an undesirable invader due to its large size, prolific seed production and vigorous growth.

It is also a health hazard to B.C. citizens—the leaves and stems contain a clear, watery, highly toxic sap that can cause hypersensitivity to sunlight resulting in burns, blisters, and scarring within 48 hours of coming into contact with skin. Touching Giant Hogweed can also cause long-term sunlight sensitivity and blindness if sap gets into a person’s eye. Read more from WCB about handling Giant Hogweed here.

Although we do not have any confirmed occurrences of Giant Hogweed in the East Kootenay, there are other native and non-native plants present that can cause skin irritation in both humans and animals, with reactions varying depending on the plant and the person.

Like Giant Hogweed, Wild Parsnip is another invasive species that contains furanocoumarin chemicals in its sap, and can cause serious reactions including reddening, blistering, and ulceration of the skin (known as phytophotodermatitis). Burns can occur if the sap contacts the skin and is then exposed to sunlight. Symptoms can occur within 48 hours and scarring and pigmentation can last for weeks and even months. This plant is found within Fernie’s city limits and in other locations in the Regional District of East Kootenay and is currently being treated.

Stinging Nettle, a native plant, is also known to cause skin reactions. This plant is covered in small hairs; and when touched those hairs “sting” with a nasty blend of histamine, serotonin, acetylcholine, and formic acid. Skin reaction of localized pain, reddish swelling, itching and numbness generally last for a few hours maximum before resolving on their own.

Poison Ivy, a less common native species, has a milky oil called urushiol (pronounced oo-roo-shee-ohl) which can cause redness, swelling and blistering of human skin within a few hours or up to 10 days after contact. Plants must be damaged in order for the oil to be emitted. Skin rashes can result from contact with either the liquid oil or its dried, blackened residue. Secondary objects such as boots, pants, hand tools or the fur of pets can also transmit the toxin.

It is important to learn to identify toxic plants in all stages and be fully aware of the precautions that should be taken to prevent exposure.

If you are exposed to any of these plant toxins, general first aid can be applied immediately:

  • If skin comes into contact with sap, wash it thoroughly with soap and water.
  • Keep pets and animals clear of toxic plants as the sap can be transferred on their fur.
  • Avoid further exposure of the affected skin to UV/sunlight.
  • If photodermatitis (burn like rash) occurs, seek medical attention.
  • If there is a chance your eyes were exposed to direct contact with the sap, immediately flush the eye with water and seek immediate medical attention.
  • If pets develop symptoms, contact your local veterinarian for treatment options.

“We really need the public’s help in reporting and identifying all invasive species,” says Jessie, “The single best thing people can do to help is to use the Report-Invasives app. The information from the app is sent directly to EKISC once it’s been screened by the Invasive Species Inter-Ministry Working Group, which then allows us to pinpoint and manage the target plant very quickly.”

Lead image: Giant Hogweed. Photo from BC Invasives


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