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Giant hogweed vs. native cow parsnip

Giant hogweed vs. native cow parsnip
Executive Director - Mon Jul 11, 2011 @ 10:03AM
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In the Sea to Sky region giant hogweed has only been found to date on a handfull of sites in the Squamish area and south, including Brittania Beach and Lions Bay.  See video below for a story on hogweed but be aware that there is a native look-alike called cow parsnip.  Native cow parsnip is common in the Sea to Sky and is a smaller version of hogweed that is generally a maximum of 5 feet when in flower.  In comparison, hogweed in flower will always be at least 6 feet tall or larger.  Some tips on identification below:

Native cow parsnip



Invasive giant hogweed



Giant hogweed vs. cow parsnip


Cow parsnip*   
Heracleum lanatum

Giant hogweed              Heracleum mantegazzianum

Height of flowering stem

3 - 6 feet

6 - 16 feet

1 – 2 m

2 – 5 m

Mature stem diameter

1 – 2 ”

2 – 4”

2.5 – 5 cm

5-10 cm

Stem hairs (not as reliable)

Fuzzy hairs

Stiff bristles

# Rays in umbel (not as reliable)

15 to 30

50 to 150

Stem colouring & leaf shape

Not diagnostic

Not diagnostic

Giant hogweed health hazard:Leaves and stems contain a clear, watery, highly toxic sap that can cause hypersensitivity to sunlight resulting in burns, blisters and scarring when coming into contact with skin.

*Cowparsnip:Possesses similar chemicals to Giant hogweed, capable of causing photosensitivity when in contact with skin (to a lesser extent but noteworthy).


For news story on giant hogweed in the Greater Vancouver area click here.


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