Giant Hogweed, Heracleum mantegazzianum

HistoryGiant Hogweed

Giant hogweed was introduced into Europe and North America from Asia in the early 1900's. Its impressive growth made it a desirable garden plant. However, giant hogweed soon escaped cultivation and established itself in natural areas in several states including Maine.

Giant hogweed is found sporadically throughout Maine with 9 counties containing confirmed infested sites.  Almost half of the known giant hogweed populations in Maine are in Hancock County.

 

A Hazardous Plant

Along with its impressive growth habit, giant hogweed is noteworthy because its sap causes severe skin irritation. When susceptible people come in contact with the sap and the skin is exposed to sunlight, painful blisters develop. 

If you must handle this plant:

  • be careful not to come into contact with sap from broken stems
  • wear gloves,
  • long sleeves,
  • long pants and
  • eye protection .

 

Identification

When identifying giant hogweed, look for the following characteristics:

  • Very tall plants, 8-14 feet in height
  • Hollow stems that are 2-4 inches in diameter with rigid hairs and purple blotches
  • Leaves that are unevenly lobed and up to 5 feet across
  • Flower clusters up to 2 feet across occurring from mid June to late July
  • Dead stems that remain upright throughout the winter

Several plants including cow parsnip, angelica and poison hemlock, look similar to giant hogweed. Pictures of giant hogweed and look-a-likes