Giant Hogweed
Giant hogweed is on the federal noxious weed list because of its dangerous sap. It threatens riparian areas by displacing native plants and exacerbating soil erosion.
Common Name: Giant hogweed
Scientific Name: Heracleum mantegazzianum
Native Range: Asia
Background
Giant hogweed (Heracleum mantegazzianum) is a member of the carrot and parsley family but do not be fooled—its sap can cause severe burns when exposed to sunlight. Thanks to its large size and equally impressive flower head, giant hogweed was introduced to Great Britain as an ornamental curiosity in the 19th century. It was later introduced to the United States and Canada as a showpiece in arboreta and Victorian gardens. One of the first known North American plantings of giant hogweed was in gardens near Highland Park in the city of Rochester, New York. Guant hogweed is on the federal noxious weed list and it appears as a prohibited plant species on several state lists.
Habitat
This plant colonizes rich, moist soils along roadside ditches, stream banks, waste areas, and forest edges.
NYS Distribution Map
NOTE: If you receive a “sign in” message, click cancel to continue. Confirmed observations of Water chestnut submitted to the NYS Invasive Species Database. For more information, visit iMapInvasives
Identification
Giant hogweed is a large, imposing plant that can grow 15-20 feet tall, making it difficult to miss. The stems have dark purple splotches, raised nodules, and are typically 1 to 3 inches in diameter, but they can be 4 inches. The leaf stalks are spotted, hollow, and covered with bristles and the leaves themselves are compound and deeply lobed. The enormous leaves can reach up to 5 feet in diameter. The plant’s large, white, umbrella-shaped flowers can be 2 ½ feet in diameter and are present from late-June to mid-July
Impact
Giant hogweed is on the federal noxious weed list because of its dangerous sap. It threatens riparian areas by displacing native plants and exacerbating soil erosion.
Prevention and Control
CAUTION: This plant contains toxic sap that can cause severe skin irritation, blistering, and scarring. Statewide control efforts are currently underway by NYSDEC and partner organizations. If you’ve found giant hogweed, please contact APIPP for management advice before treating it on your own.
Native Lookalikes
There are several species that closely resemble giant hogweed including cow parsnip, angelica, wild parsnip, Queen Anne’s lace, and poison hemlock.
Additional Information
- Invasive Species Best Management Practices
- Giant Hogweed Identification: This page has photos of all parts of the giant hogweed plant as well as photos of common lookalike plants for identification purposes.
- Health Hazards & Safety Instructions for Giant Hogweed (with graphic photos): This page describes the health hazards of giant hogweed and details how people should protect themselves against the harmful sap.
- How To Control Giant Hogweed: A variety of methods for controlling this non-native invasive plant.
- Giant Hogweed Biology:This page describes the biology of giant hogweed plants, including their growth and devlopment stages, seed dispersal and viability, as well as the habitat and competition for giant hogweed plants.
