Giant Hogweed

Heracleum mantegazzianum

Giant hogweed has only been reported in Watuga County, North Carolina but it has caused problems in both the northeast and the Pacific Northwest and is listed as a federal noxious weed. The plant’s sap is poisonous and can cause severe burns and blindness. It also produces a dense canopy which shades out native species. One plant produces many seeds which are dispersed by wind and water. It commonly invades open areas with moist disturbed soils, such as those in fields, along stream banks, roadsides, and ditches. It is much easier to control an invasive species if we can manage infestations when they are still small. So, please watch out for giant hogweed and report any infestations to the N.C. Department of Agriculture and Consumer Services Weed Specialist at 1-800-206-9333.

Giant hogweed is a massive plant; it usually only lives for 2 years but it can grow to a height of 15’ and has enormous leaves and flower clusters. The large flat cluster, umbel, of small white flowers is reminiscent of Queen Anne’s Lace, but giant hogweed’s umbel is much larger, growing up to 2½’ in diameter.  It blooms in midsummer. Its leaves are compound and arranged alternately along the stem. Each leaf is made up of 3 deeply incised leaflets which can grow as large as 5’ wide. The leaflets near the top of the stem are less incised and not as large. The stems are ridged, hollow and have purple spots on them. Fine white hairs grow at the nodes in the stem. 

It is important to wear protective clothing and eyewear when handling this plant!

Fact Sheet: Giant Hogweed

Photo credit (left panel): Terry English, USDA APHIS PPQ, Bugwood.org

Photo credit (rigth panel): Thomas B. Denholm, New Jersey Department of Agriculture, Bugwood.org