Giant Hogweed Overview
Giant Hogweed was introduced into North America in the early 1900s. Its native range is Central Asia, although now it occurs throughout the United Kingdom, Australia, Europe, parts of Canada and the United States. It is suspected to have made its way into this country as an ornamental. Its size made it somewhat of an oddity and gardeners that wanted something unique imported it.
Giant Hogweed is a public health hazard that ranks up there higher than poison ivy, poison oak and poison sumac in respect to its potential to harm humans. The reason for concern is that the sap from this plant can cause a severe skin reaction known as photo-dermatitis or photo-sensitivity. The reaction can happen up to 48 hours after contact. After coming in contact with the sap, the skin blisters when exposed to sunlight. Contact with the eyes can lead to temporary or possibly permanent blindness. The weed can be especially troublesome for children that may find the long stems attractive to play with. If you do come into contact with the plant, and especially the sap, you are advised to wash the affected areas immediately, keep the exposed area out of direct sunlight and seek medical advice.
Besides these public health concerns, Giant Hogweed is also reported to be invasive under certain conditions. It does especially well in disturbed soils and also along waterways where seeds can be spread long distances. Large colonies have been known to form from a single plant, where an abundance of seeds coupled with shoots arising from the roots gives rise to dozens of offspring. Weed specialists have reported that once it becomes established, it takes up to five years to completely eradicate a colony due to regrowth from seeds and roots.
This unwanted plant is found on the Federal Noxious weed list. This means that it is illegal to sell or transport it across state lines, a violation punishable by fines.
Giant hogweed has already been detected in many counties across Michigan. Funding to support the detection, identification, or control of Giant Hogweed is no longer available to the Michigan Department of Agriculture and Rural Development (MDARD). Active management of Giant Hogweed on the sites where it is known to occur in Michigan is the responsibility of the proper owner/manager.
How Do You Know If It's Really Giant Hogweed? Proper identification is an important first step. A number of common plant species resemble Giant Hogweed, but there are ways to tell them from the real thing. Only approximately 2% of suspect plants submitted to MDARD for identification are confirmed as Giant Hogweed.
Here are a few guides you may find useful. (Please review the material in the guides before contacting MDARD about suspect Giant Hogweed):
If you have seen a plant that appears to be Giant Hogweed and need help identifying it, send an email to MDA-Info@Michigan.gov, along with any pictures, so that it can be examined by professional staff of MDARD. (Please e-mail four pictures: 1. Whole plant, 2. Leaf, 3. Flower/seed head, 4. Where a leaf joins the stem.) Please note: The maximum size of your email cannot exceed 25 MB.
You can also call 1-800-292-3939.