5 poisonous plants of Southern Ontario you should...
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Jul 21, 2015  |  Vote 0    0

5 poisonous plants of Southern Ontario you should avoid


As temperatures climb this summer, traffic on the hiking trails will only increase.

But a hike could bring on illness, or a hospital stay if you get your hands, or other body parts, on any of the poisonous plants that grow across Southern Ontario.

Some of them may look harmless, and sometimes even beautiful, but contact with these plants can cause symptoms ranging from itching, irritating, and sometimes painful rashes to extremely dangerous if ingested.

There are several species of poisonous plants in Ontario. Here are some of the most common ones you need to know before you head out:


1. Poison Ivy


Description: The saying "leaves of three, let it be" warns you to keep away from this dreaded plant. Leaves are glossy green, alternate and consist of three leaflets with the middle leaflet having a much longer stalk. The edges of the leaves may be smooth or toothed.

Where: Along the forest edge, in meadows, forest openings and trails.

Adverse effects: Poison ivy is a very common trigger of allergic contact dermatitis or inflammation of the skin. It contains the potent antigen urushiol, which will cause a reaction in 60 to 80 percent of the people who are exposed to it. Oil resin from the plant may be carried on any object it comes in contact with – clothing, shoes or pet fur - and then transferred to the skin.


2. Giant Hogweed


Description: This invasive plant can reach heights of 4 to 5 metres and has a reddish-purple stem measuring from 5 to 10 centimetres in diameter. It flowers from June to September and has a cluster of flowers measuring up to 1.1 metres across. Each cluster will have 30–20 flowers.

Where: Giant hogweed can be found along roadsides, trails and stream banks.

Adverse effects: If you come in contact with this plant, you may experience severe burns to your skin. The sap found in giant hogweed contains furocoumarins that cause serious skin inflammation activated by exposure to the sun.


3. Wild Parsnip


Description: Wild parsnip grows from 50 to 150 centimetres high, has compound leaves that are arranged alternately on the stem and leaves that are mitten-shaped. Yellow flowers form a flat-topped umbrella-like cluster and are seen from late May to early fall. The wild parsnip has a distinctive parsnip odour.

Where: Generally found along the edges of plantations, roadsides, meadows and in old pastures.

Adverse effects: Similar to the giant hogweed, wild parsnip contains furocoumarins that when absorbed by the skin, and stimulated by ultraviolet light, the furocoumarins begin destroying cells and skin tissue, which appears as redness and blistering of the skin.


4. Pokeweed


Description: Pokeweed has a red trunk-like stem, which becomes hollow as the plant matures. Egg-shaped leaves are large (25 centimetres long), dark green, alternate and attached to the stem by a red stalk. Flowers appear green to white and the fruit is green, turning a deep purple to black as it matures.

Where: Meadows, edges of woods and waste areas in the Southwestern Ontario.

Adverse effects: Pokeweed is poisonous to humans and animals. Symptoms of pokeweed poisoning include sweating, blurred vision, abdominal pains, weakness, vomiting and unconsciousness.


5. Spotted Water Hemlock


Description: The water hemlock grows up to 2.2 metres tall, with small, white flowers shaped like an inverted umbrella that bloom from July to August. This plant has alternate, coarsely-toothed leaves and a stout, green stem spotted with purple that seeps a yellow oily liquid when cut.

Where: Marshes, swamps, stream banks, ditches, moist thickets and meadows throughout Ontario

Adverse effects: The plant contains cicutoxin, a toxic alcohol that attacks the central nervous system. Symptoms of poisoning appear quickly and include extreme salivation, violent convulsions, intense abdominal pain and delirium. Coma and respiratory failure can develop from 30 minutes to eight hours afterwards.

This summer, take preventative measures and learn how to identify, avoid and treat reactions from poisonous plants to protect your health in the outdoors.

If you require assistance identifying a plant, you can take a photo and submit it along with its location to the Ontario Ministry of Agriculture, Food and Rural Affairs' (OMAFRA) online weed identification service at www.weedinfo.ca

If you believe you or a child has touched or consumed a poisonous plant, you should call the Ontario Poison Centre immediately at 1- 800-268-9017 for assistance.

Originally published March 25, 2015

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(2) Comment

By Tony | JULY 21, 2015 12:50 PM
How about posting some pictures of beneficial plants? For example, jewelweed grows near poison ivy and is the best antidote for poison ivy! I had a terrible case a few years ago and topical cortisone creams wouldn't even dampen the itching. One bar of Burt's Bees Poison Ivy Soap, made with jewelweed, took care of it and kept it from coming back!
By Tom | JULY 21, 2015 12:11 PM
Don't forget about stinging nettle. It's making a comeback...
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