Giant Hogweed

(Heracleum mantegazzianum)

Approach with caution, as the sap of this plant contains a toxin that is activated by sunlight and can cause serious lesions on the skin (burns).

The Giant Hogweed plant was introduced to the province of Quebec and is highly invasive.  It can be found on vacant lots, in ditches, wetlands and fields.

Here are several tips on how to recognize the Giant Hogweed plant:

  • It stands anywhere from 2 to 5 meters tall;
  • The leaves can reach 1.5 to 3 meters in length;
  • Its umbrellas (flowers) measure 25 to 50 cm and the stem is dotted with red spots.

Be careful not to confuse her with her cousin, the Cow Parsnip.  The latter is an indigenous plant.  Although it is not invasive and is less toxic, it can also cause lesions on skin.

The following are some clues and photographs to help you differentiate Cow Parsnip from its alien cousin:

  • Cow Parsnip stands no taller than 3 meters;
  • The stem is covered with soft and wooly white hairs;
  • Its leaves are smaller and less serrated.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Control method
First, avoid planting or sowing this plant.

Special precautions
To get rid of Giant Hogweed, you must handle it with great care.  Wear gloves and cover all parts of your body with clothing made of synthetic and waterproof materials.  If you come into contact with the sap of this plant, wash the affected area immediately and limit your exposure to the sun for the next 48 hours.

Use a knife or a spade to cut the stems about 15 cm above the ground.  Remove the roots with your shovel.

Place the plants into black plastic bags and, to destroy them, leave the bags in the sun for a week before putting them into the garbage can.

When there are flowers present, place these in airtight plastic bags before cutting the stems.  This will help prevent the spread of pollen and seeds.

Do not put them into the brown bin (compost) because the seeds could propagate.

Finally, do not leave the soil bare (without vegetation).  Plant indigenous species quickly for it may take several years to eradicate the Giant hogweed.

Report your observations
If you suspect the presence of Giant Hogweed, contact the Municipality by email (environement@rawdon.ca) or by telephone at 450 834-2596 ext. #7136.  The Municipality is responsible for identifying this invasive plant species with the Sentinelle network of the ministère du Développement durable, de l’Environnement et de la Lutte contre les changements climatiques (MDDELCC). In addition, we can support you in your efforts to eradicate this toxic plant.

For more information, please visit the following links from the MDDELCC website:

  1. La Berce du Caucase
  2. Portail Santé mieux-être : Reconnaître et éliminer la berce du Caucase