Giant Hogweed and Wild Parsnip

Many plants can easily be mistaken for Giant Hogweed and Wild Parsnip, including Angelica, Cow Parsnip, and Queen Anne's Lace. 

See the additional resources at the bottom of this page to learn how to identify these plants.

Both Giant Hogweed and Wild Parsnip can be dangerous to touch. 

• Town of Oakville Giant Hogweed and Wild Parsnip Safety Alert (pdf)
• Toxic Plants Caution Sign (pdf)

Giant Hogweed

Identifying features

Giant Hogweed is a large, invasive plant that can grow up to six metres tall. It has a thick stem with reddish spots and large, cabbage-like leaves. Its white flower clusters and seed heads are distinguished by their rounded umbel shape and size of up to one metre across.

Health risks

Giant Hogweed's sap contains chemicals that can cause skin to become hypersensitive to sunlight and erupt in painful blisters. If you see this plant, do not touch it. If you come in contact with the plant, you should thoroughly wash exposed skin with soap and water and keep the affected area out of direct sunlight for at least 48 hours. If your skin reacts or becomes painful, seek medical attention.

Report sightings

The town has installed signs in areas where Giant Hogweed has been found. If you stay on established park paths and groomed trails on town property, you should not encounter Giant Hogweed. If you come across Giant Hogweed on town property, do not attempt to remove it. Instead, inform ServiceOakville at 905-845-6601. They will notify the appropriate town staff who will confirm plant identification, report to Conservation Halton for tracking, and treat the area as appropriate.

The Town of Oakville partners with Conservation Halton to control Giant Hogweed with herbicide application. 

Wild Parsnip

Identifying features

Wild Parsnip is an invasive plant that can grow up to 1.5 metres tall. It has a smooth single green stem 2 to 5 centimetres thick, and compound leaves with sharply toothed leaflets that resemble mittens. It can be distinguished from its look-alikes during flowering season by its yellowish-green umbrella-shaped flower clusters 10-20 centimetres across.

Health risks

Contact with the sap of the plant may cause skin irritations, burns or blisters. As with Giant Hogweed, you should avoid touching this plant with any exposed skin. If you are exposed to sap from the plant, you should immediately and thoroughly wash the exposed skin with soap and water, avoid direct sunlight on the affected area and seek medical attention if you have a reaction to the sap.

Report sightings

Wild Parsnip is present in most open and naturalized areas throughout town. Its abundance makes control almost impossible. The town is limiting control treatment to groomed park space and areas within two metres of granular and paved trails and walkways. Extreme caution should be exercised if using foot trails not maintained by the town and in all naturalized spaces.

If you identify wild parsnip on town property, please call ServiceOakville at 905-845-6601 and provide the closest address and approximate size of the affected area. Do not attempt to remove or touch the plant.