Both of the Carrot Family (Apiaceae), it’s no wonder giant hogweed and cow- parsnip are mistaken for one another. Not only do they share similarities in appearance, but they prefer the same growing environments – roadsides, wood edges, ditches, and floodplains. Despite this, cow-parsnip is a native species and serves as a highly important pollen and nectar source for many bees and wasps. Giant hogweed, on the other hand, is highly invasive and easily out-competes nearby vegetation. Additionally, its sap causes chemical burns after the affected area is exposed to sunlight – a major reason for learning proper identification!
Giant Hogweed (Heracleum mantegazzianum)
Introduced as an ornamental in the early twentieth century and native to Asia, it is now prohibited under Michigan law.
Flowers- June and July, small and white, head is 8-20 inches across
Height- Can grow up to 20 feet tall
Leaves- Alternate, coarsely toothed and deeply lobed, divided into 1-3 large leaflets
Cow-parsnip (Heracleum maximum)
While still large compared to many other native plants, it is not nearly as tall as giant hogweed. Coming in contact can also result in photo-sensitivity but to a lesser degree. One must break open the plant to be exposed to the sap, whereas, just brushing up against hogweed can cause rashes.
Flowers- May and June, small and white, head is 2-8 inches across
Height- Can grow up to 9 feet tall
Leaves- Leaves divided into 3-5 coarsely toothed, lobed leaflets
To learn about several other look-a-likes, visit this site!
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