Click below to listen to my Garden Bite radio show: MDA October weed of the month – Giant hogweed
The Minnesota Department of Agriculture has been highlighting a weed each month. This month, they’re being proactive as this weed has not YET been found in Minnesota but is in neighboring Wisconsin. The Giant hogweed – Heracleum mantegazzianum [Now you know why I didn't even ATTEMPT to say this on my show!] Native to Central Asia, Giant hogweed, was introduced to Britain as an ornamental in the 19th century, and it has also spread to many other parts of Europe, the United States and Canada.
Giant hogweed flower
It’s a stunningly tall plant with a serious public health risk. When the sap comes in contact with skin and is exposed to sunlight, it can cause painful blisters and scarring. Additionally, the sap in contact with eyes can result in blindness.
Giant hogweed burn and this is MILD
I didn’t want to put some of the other pictures here because it’s really kinda gross… you can google it on your own!
This thing is HUGE! Giant hogweed has many identifiable characteristics including deeply cut massive leaves up to five feet across. The plant flowers on a 10-15 foot stalk. The tiny white flowers form clusters that reach up to two and a half feet across. The stalks are two inches in diameter and hollow with purple mottling. Both the stems and undersides of the leaves are covered in coarse white hairs. It can be mistaken for Cow Parsnip (Heracleum maximum), a native plant that is common throughout much of Minnesota, has similar leaves and flowers, and reaches 3-10 feet tall with 4-8 inch flowers. However, giant hogweed has much larger, strongly dissected leaves and huge flowers.
Giant hogweed leaf
Giant hogweed bud\
Not only is giant hogweed a serious public health hazard, it can also negatively impact soil dynamics, fisheries, and outcompete native plants. In states where it has been confirmed, it can be found growing in yards, ditches, along stream banks, in disturbed areas, open wooded areas, and thrives in sunny locations. Giant hogweed spreads by seed that can be moved by wind, water, wildlife, and humans.
Even though this plant has not yet been discovered in Minnesota, the Minnesota Department of Agriculture regulates giant hogweed as a prohibited noxious weed on the eradicate list because of its close proximity of establishment in Wisconsin. It is also a Federal Noxious Weed regulated by the U.S. Department of Agriculture. By law, all above and below ground plant parts must be destroyed, and no transportation, propagation, or sale of the plants is allowed. If you suspect you have seen giant hogweed, please contact the MDA’s Arrest the Pest voicemail at 888-545-6684 or email firstname.lastname@example.org.