Hogweed: An Unwelcome and Aggressive Plant With Bad Manners
Beautiful gardens and well designed landscaping can turn a yard into a wonderland. Many gardeners and gardens turn to other parts of the world to find beautiful and exotic plants for their yard. Exotic plants have led to many beautiful gardens and some giant headaches. A lot of plants from elsewhere escape from domestic gardens and go rouge. There are some plants that have invaded the North East of the United States. Boston landscaping and MA landscaping in general have had close calls with troublesome species. One of the most worrisome plants is Giant Hogweed.
Giant Hogweed, (Herculeum Mantegazzianum) has been found in Massachusetts and other other states. It is an aggressive plant that quickly dominates habitats and crowds out native plants. It appears similar to Cow Parsnip (Herculeum Maximum) in the land of giants. While Cow Parsnip is a large decent sized plant averaging 4-5 feet in height with the ability to grow to 8 feet, the Giant Hogweed isenormous. It can grow between 10 and 15 feet tall with huge flowering heads measuring 2 and a half feet across. Its leaves can spread up to five feet across. It is an impressive plant that turns people into Lilliputians . At least that’s what it feels like standing under one.
Giant Hogweed comes from the Caucasus Region and Central Asia. It has become a dominant plant in parts of Britain and has invaded the Northeast and Northwest regions of the United States. Aside from its aggressive growth and habitat invasion, the Giant Hogweed is also a toxic plant harmful to animals and humans. The juice of the Giant Hogweed is clear and watery. It is also a phototoxic weed. It’s not a threat to photography, but it could cause some serious damage to your skin. Phototoxicity means that the sap interacts with sunlight, mainly the ultra violet rays. It can cause severe itching, blistering and even scaring that can last for several years. If the sap gets in the eye, it can result in blindness. In the liquid is a substance, derivatives of furocumarin, whichenter into epithelial cells, attach to the DNA and cause the cells to die. Similar to a chemical burn it chars the skin deep brown.
Since it is both invasive and toxic, it has earned a spot on the Federal Noxious Weed list and is slated for eradication wherever it is found.
Since Common Cow Parsnip and Giant Hogweed, (also referred to as Giant Cow Parsnip) look alike, it is worth understanding the differences. The first obvious difference is the scale. But both are root and shoot perennials. This means that they die back each winter and send up new shoots in the spring. Since Giant Hogweed doesn’t start out 15 feet tall it’s important to note some of the differences. The distinctive marks of Giant Hogweed is purple spots on on a hollow stalk that can grow from 2 to 4 inches in diameter. Herculeum Maximum has no spots and the hollow stalk seldom gets bigger the 2 inches. Giant Parsnip has short hairs underneath its leaves while Cow Parsnip has a profusion of long hairs.
If you come across a stand of Giant Hogweed, don’t hesitate to get in touch with the appropriate local agency or the Department of Natural Resources. Giant Hogweed should be treated like poison oak and poison ivy, washing with soap and water and avoiding contact when possible.