Giant hogweed (Heracleum mantegazzianum) looks similar to Queen-Anne’s Lace (Daucus carota) and belongs to the carrot family. This species can be found in a variety of habitat from riverbanks, fields, roadsides, and along streams. It can grow up to 8 feet tall and have lobed ‘lacey’ leaves 5 feet across. The large white flower heads are comprised of small clusters of flowers and can be 2 feet in diameter. The stem is green with purple splotches.
The state of New York has a great resource for common lookalikes for giant hogweed.
Have you seen this species? Report it to us or on the MISIN website or smartphone app! Please include a photo to aid in ID verification.
Environmental Impacts
Giant hogweed outcompetes native species which lowers plant diversity. A single plant can produce 50,000 seeds in one growing season. The large leaves shade the understory and prevent growth which can lead to soil erosion. This is especially an issue along stream banks.
Treatments
Giant hogweed sap can cause severe reactions to human skin when it comes into contact with sunlight. Extreme caution must be taken when treating this species. There are multiple treatment options including chemical and non-chemical.
NON-CHEMICAL CONTROL METHODS
- Hand digging: small patches can be removed by hand digging. It is important to remove as much of the root system as possible to prevent regrowth. It is best to follow up on the site condition and retreat the area several times a season and the following year as well. Note: it is best to begin hand digging between March and July.
CHEMICAL CONTROL METHODS
Foliar spraying: herbicide is sprayed directly onto the foliage of the plant. This is the most common treatment for large patches, often done by contractors. This method should be carried out from April to June. Note: herbicide will kill surrounding vegetation if it comes into contact with its leaves.