Giant Hogweed (2024)

Do Not Touch This Plant!

Giant hogweed (Heracleum mantegazzianum) is a VERY LARGE, invasive plant that can cause painful burns and permanent scarring. Brushing against or breaking the plant releases sap that, combined with sunlight and moisture, can cause a severe burn within 24 to 48 hours. Giant hogweed is a Federally listed noxious weed and NYS law prohibits its possession with the intent to sell, import, purchase, transport, introduce or propagate.

What to do if You Come in Contact With Giant Hogweed

Wash the affected area thoroughly with soap and COLD water as soon as possible
Keep exposed area covered or away from sunlight for 48 hours
If a reaction occurs, topical steroids applied early can reduce the severity of the reaction and ease discomfort
If a reaction has occurred, the area of skin may be sensitive to sunlight for a few years and you may want to apply sun block or keep the affected area covered from the sun when possible
See a physician if you have a reaction or any questions
If sap goes in eyes, rinse them with water, wear sunglasses or cover your eyes, and seek emergency medical care IMMEDIATELY to prevent potential blindness

Description

Giant hogweed is a biennial or perennial herb in the carrot family (Apiaceae) which can grow to 14 feet or more. Its hollow, ridged stems grow 2-4 inches in diameter and have dark reddish-purple blotches. Its large compound leaves can grow up to 5 feet wide. Its white flower heads can grow up to 2 1/2 feet in diameter. Some other plants look very similar.

Lookalikes

Giant Hogweed and Common Lookalikes
Plant	Flower	Leaf	Stem
Giant Hogweed 7-14 feet tall This plant can cause burns. Do not touch.	White umbrella-shaped flower clusters up to 2.5 feet wide. 50+ rays per cluster. Flowers late June - mid July	Compound, lobed, deeply incised, up to 5 feet wide	Green with purple splotches and coarse white hairs - thick circle of hairs at base of leaf stalk, 2-4 inches in diameter.
Cow Parsnip 5 to 8 feet tall This plant may cause burns.	White flat-topped flower clusters no longer than one foot wide. 15-30 rays per cluster. Flowers late May - Late June	Compound, less incised than hogweed, between 2 - 2.5 feet wide	Green and rigid with fine white hairs 1-2 inches in diameter.
Angelica 4 to 9 feet tall This plant may cause burns.	Softball-sized and shaped clusters, greenish-white or white Flowers mid May - mid June	Compound leaves that may extend up to 2 feet wide	Smooth, waxy purple, 1 to 2.5 inches in diameter (no hairs or bristles)
Wild Parsnip Up to 5 feet tall Native of Eurasia This plant can cause burns. Do not touch.	Single flower stalk with flat-topped umbel of yellow flower clusters Flowers late May - early July	Compound, pinnate, 5 to 15 toothed leaflets, variably lobed, yellowish-green	Yellowish-green with full length grooves (no hairs or bristles)
Queen Anne's Lace 1 to 3 feet tall Native of Eurasia	Flat-topped umbel of white flower clusters, 2 to 4 inches wide. The central flower cluster usually deep purple. When fruiting, the umbel becomes concave and resembles a "bird's nest."	Compound, pinnate, fern-like.	Green, covered with bristly hairs.
Poison Hemlock 4 to 9 feet tall Native of Eurasia All parts of this plant are very poisonous. DO NOT INGEST	Small and white arranged in numerous flat-topped clusters on all branches Flowers late May - late June	Bright green, small and fern-like, may appear glossy	Smooth and waxy stem with purple blotches, 1 to 2 inches in diameter (no hairs or bristles)
Common Elderberry Shrubs 5 to 12 feet tall Spreads and forms thickets	White flat-topped or slightly rounded flower clusters at branch ends, 2 to 6 inches wide. Fruit is purple to black in color. Flowers June - July	Compound, pinnate, 5 to 11 toothed leaflets	Older woody stems or young green stems with prominent lenticels (pores), no hairs or bristles
Pokeweed Up to 10 feet tall All parts of the plant are poisonous. DO NOT INGEST	Greenish-white racemes (linear flower clusters), with dark purple berries. Flowers late June - October	Alternate, large, entire leaves (not leaflets)	Green to red or purplish, smooth stout stems, no hairs or bristles

Distribution and Habitat

Giant hogweed is a native of the Caucasus Mountain region between the Black and Caspian Seas. It was introduced to the United States in the early twentieth century as an ornamental garden plant. It has become established in New England, the Mid-Atlantic Region, and the Northwest. Giant hogweed grows along streams and rivers, as well as in fields, forests, yards, and near roadsides. It grows in sunny areas and in partial shade, preferring moist soils.

Management

From late April through August, DEC field crews visit each confirmed giant hogweed site, and use the appropriate control method. This is free of charge to the landowner. In general management is decided by the size and number of plants:

root-cutting is used at smaller sites with less than 400 plants,
herbicide is used at larger sites with greater than 400 plants; and
flower/seed head removal is used at all sites to limit seed dispersal.

Sites are visited each year until the plants are eradicated. When no more plants are found the site will be monitored for three subsequent years.

For a site to be visited and controlled, landowners must give annual permission. For crews to use herbicide control, landowners must first sign a property permission form.

Past years' annual reports:

What You Can Do To Help

Report Giant Hogweed

If you see giant hogweed, take a picture and email DEC or call the Giant Hogweed Information Line: 845-256-3111. Provide photos, detailed directions to the plant infestation (GPS coordinates and street address preferred) and estimate the number of plants.

DEC has giant hogweed publications for distribution. Email DEC or call the Giant Hogweed Information Line at 845-256-3111 to let us know how many brochures and posters you can use. Provide your mailing address so we can mail them to you.