giant hogweed
(Heracleum mantegazzianum)
This species is Introduced in the United States
Heracleum mantegazzianum is a herbaceous biennial or monocarpic perennial that can grow up to 15-20 ft. (4.3-5.8 m) in height. The stem is hollow and usually blotched with purple. Both the leaf stalks and stem produce pustulate bristles. The stem can be 2-4 in. (4.8-9.6 cm) in diameter.
Foliage
The leaves are ternate or ternate-pinnate with pinnately lobed lateral segments. They can be up to 9.8 ft. (3 m) in breadth.
Flowers
Heracleum mantegazzianum flowers from June-July. The inflorescence has many white florets (with petals about 0.4 in. [1 cm]) that form a flat-topped umbel. Each inflorescence can have a diameter of up to 2.5 ft. (0.72 m).
Fruit
The fruits are dry and elliptic, measuring 0.3-0.4 in. (8-11 mm) long and 0.25-0.3 in. (6-8 mm) wide. The fruits have brown resin canals that can be up to 0.04 in. (1 mm) in diameter.
Ecological Threat
Heracleum mantegazzianum can outcompete species for habitat, especially in riparian zones, and it may cause increased soil erosion. This plant is on the federal noxious weed list because of its poisonous sap. This sap makes the skin very sensitive to UV radiation, causing blistering and severe burns. Caution should be taken when handling this weed. Removing it manually becomes very difficult because of the danger caused by its sap.
Citations
Rawlins, K.A., R.L. Winston, C.T. Bargeron, D.J. Moorhead, and R. Carroll. 2018. New Invaders of the Southeast. USDA Forest Service, Forest Health Assessment and Applied Sciences Team, Morgantown, West Virginia. FHTET-2017-05. Retrieved from http://bugwoodcloud.org/resource/pdf/FHTET-2017-05_New%20Invaders_SE.pdf
Winston, R.L., Andreas, J.E., Milan, J., DesCamp, W., Randell, C.B., and M. Schwarzländer. 2014. New Invaders of the Northwest. United States Department of Agriculture, Forest Health Technology Enterprise Team. FHTET-2014-12. Retrieved from https://www.fs.fed.us/foresthealth/technology/pdfs/FHTET-2014-12_NW_New_Invaders.pdf
Resources
- Domestic Programs Pest Evaluation - USDA APHIS PPQ
- Fact Sheet - USDA APHIS PPQ
- Federal Noxious Weed Disseminules of the U.S. - USDA-APHIS
- Weed of the Week - USDA Forest Service
- Plant Invaders of Mid-Atlantic Natural Areas - National Park Service and U.S. Fish and Wildlife Service
- Fact Sheet - Ontarios Invading Species Awareness Program
- Best Management Practices - Ontarios Invading Species Awareness Program
Selected Images
Maps
EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org
State Lists - This map identifies those states that have this species on their invasive species list or law.
Invasive Listing Sources
- Alberta Weed Control Act
- California Invasive Plant Council
- City of Ann Arbor Michigan Parks and Recreation
- Commonwealth of Pennsylvania, Department of Conservation and Natural Resources, 1994.
- Connecticut Invasive Plant List
- Connecticut Invasive Plant Working Group
- Federal Noxious Weeds
- Florida Noxious Weeds
- Idaho Noxious Weeds
- Illinois Exotic Weed Act
- Indiana Invasive Species Council - Invasive Plant List
- Iowa Forest Invasive Plants
- Maryland Department of Natural Resources Policy: Restriction on Planting Exotic Invasive Plants
- Maryland Invasive Species Council - Invasive Species of Concern in Maryland
- Massachusetts Invasive Plants Advisory Group List
- Massachusetts Noxious Weeds
- Massachusetts Prohibited Plant List
- Michigan’s Prohibited and Restricted Species
- Mid-Atlantic Field Guide to Aquatic Invasive Species
- Minnesota Noxious Weeds
- National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
- National Park Service, National Capital Region Exotic Plant Management Team Invasive Plant List
- Native Plant Society of Oregon, 2008
- New Hampshire Invasive Species Committee. 2005. Guide to Invasive Upland Plant Species in New Hampshire. New Hampshire Department of Agriculture, Markets and Food Plant Industry Division and New Hampshire Invasive Species Committee.
- New Hampshire Prohibited Invasive Species
- New Invaders of the Northwest
- New Invaders of the Southeast
- New Jersey Invasive Species Strike Team 2017 Invasive Species List
- New York Regulated and Prohibited Invasive Species - Prohibited
- Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
- Ohio Noxious Weeds
- Ontario’s Invading Species Awareness Program Tracked Species List
- Oregon Noxious Weeds
- Pacific Northwest Exotic Pest Plant Council, 1998
- Pennsylvania Department of Conservation and Natural Resources Invasive Plants
- Pennsylvania Noxious Weeds
- Pennsylvania Regulations for Controlled Plants and Noxious Weeds
- Plant Invaders of Mid-Atlantic Natural Areas
- Rhode Island Natural History Survey
- South Carolina Plant Pest List
- Tennessee Exotic Pest Plant Council
- USDA APHIS Regulated Pest List
- Virginia Invasive Plant Species List
- Virginia Invasive Species Management Plan 2012
- Virginia Noxious Weeds
- Virginia Regulations for Enforcement of Noxious Weeds Law
- Washington Noxious Weeds
- WeedUS - Database of Plants Invading Natural Areas in the United States
- Wisconsin Noxious Weeds
- Wisconsin's Invasive species rule – NR 40
Taxonomic Rank
| Domain: Eukarya |
| Kingdom: Plantae |
| Phylum: Magnoliophyta |
| Class: Magnoliopsida |
| Superorder: Asteranae |
| Order: Apiales |
| Family: Apiaceae |
| Genus: Heracleum |
| Heracleum mantegazzianum |
References
Common Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.
Scientific Name Reference: USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.