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Questions and Answers: 2016

Question: We have a growing number of a tall plant in Mount Holly, VT that some say is Giant Hogweed while …

• Question

  We have a growing number of a tall plant in Mount Holly, VT that some say is Giant Hogweed while others say it is cow parsnip. The sap is toxic, causing blisters. Here are my questions: (1) How do we definitively determine which plant it is? (2) Should we be trying to eradicate it, regardless of which it is? Or only if it is Giant Hogweed?

  Answer

  Dear davidsmartin, good morning. To identify which species you have, you would need to observe the characteristics that distinguish these two species. The key characteristics are as follows: 1a. Umbel with mostly 50–150 primary branches, up to 50 cm wide; leaflets of principal leaves up to 130 cm long; schizocarp on a pedicel 15–40 mm long, with oil tubes 0.8 mm wide or wider that extend (50–) 65–75% of the way from apex to base of mature fruit . . . . . H. mantegazzianum 1b. Umbel with mostly 15–45 primary branches, rarely exceeding 20 cm wide; leaflets of principal leaves 5–30 (–60) cm long; schizocarp on a pedicel 6–20 mm long, with oil tubes up to 0.5 (–0.8) mm wide that extend 50–60 (–70%) of the way from apex to base of mature fruit ..... H. maximum I would not eradicate native plants because someone, somewhere in the world is sensitive to it. Most people have no problem with our native Heracleum maximum. For example, I contact this species frequently during the growing season and even eat this plant without any issue. It would be best that those rare individuals who might be sensitive to the sap of this plant to learn its identification and avoid the plants rather than cleansing the landscape of all possible hazards for all people. If you need any assistance identifying the plants, I'm happy to help you. Feel free to email me at ahaines[at]newenglandwild.org and we can discuss this further. Best wishes.