Identifying and Fighting Invasive Species

By Jenevra Wetmore

If you have driven on the roads of Vermont lately, you have probably noticed tall yellow flowers blossoming along roadsides and in pastures. This weed, commonly known as “wild parsnip” or “poison parsnip,” is an invasive plant from Europe and Asia that has escaped gardens to make its home in Vermont. June through August is the most common time to spot the plant, which can grow 5-feet tall. Its flower is in the shape of an umbel, similar to Queen Anne’s Lace, and is bright yellow. Those familiar with poison parsnip know not to touch it without protective clothing, including gloves, long sleeves, pants, boots and eye protection. This is because poison parsnip, or Pastinaca sativa, has phytophotosensitive sap. This long word means that, if the plant’s sap gets on your skin and is exposed to sunlight, it can cause painful rashes, blisters and even second-degree chemical burns within 24 to 48 hours. Poison Parsnip is found throughout North America, including every county in Vermont. 

The USGS defines an invasive species as an introduced non-native species of plant, animal, disease, or parasite that spreads or expands its range from the site of its original introduction, and has potential to cause harm to the environment, economy or human health. Invasive plants threaten our forests, our lakes, ponds and rivers. They also threaten our human-created spaces, such as parks, lawns and agricultural crops and fields. For example, poison parsnip is not only a threat to human health, but also crowds out other native plants and ruins hay fields, spreading quickly to dominate an area. It is also poisonous to grazing livestock.

The list of invasive species in Vermont is terrifyingly long. Some of the most common offenders to look out for are: barberry, common and glossy buckthorn, Japanese knotweed, shrub honeysuckle, purple loosestrife, garlic mustard, bittersweet, multiflora rose and yellow flag iris. This is by no means a comprehensive list, and does not include the invasive diseases, pests and many aquatic plants and animals that are in Vermont. You can see pictures and learn about identification and management of these species and more by visiting 

Once you learn to identify an invasive species you will begin seeing it everywhere. I recently learned how to identify goutweed (aka Bishop’s weed) after moving into a home with patches of the plant, which is unfortunately quite pretty looking until you watch it suffocate your surrounding plants. Goutweed is not listed as an invasive species in Vermont, but is instead classified as a Class B Noxious Weed and is banned from being sold. Now that I know, I have begun pointing it out when I visit people’s homes. This makes me an unpopular houseguest, and raises the question: once you identify an invasive species, what can be done? 

The method of control for an invasive species depends on what species you are attempting to manage. Always research a plant before attempting to manage it! Some invasive species are incredibly difficult and likely require professional help, such as Japanese knotweed, which can spread through nodes in pieces of the stem in soil or water. Some have made the mistake of cutting a patch down and throwing the stems in a pile, only to create another patch of knotweed elsewhere. In addition, be aware of the dangers of using pesticides, both to yourself and to surrounding wildlife. Manual control is always safer than chemical.

Other invasive species are more manageable. You can uproot barberry, buckthorn and honeysuckle bushes, provided they are young enough to dig with a shovel. For poison parsnip, pulling the plant up by the root with the help of a shovel before it goes to seed is incredibly effective, especially if it is not already well established in an area (while keeping in mind the dangerous properties of its sap, of course).  I am currently covering patches of goutweed in my yard with weighted-down black tarps, which I plan to leave on for two years to kill the plant. Managing invasive species is frustrating, but rewarding when you know the many benefits to humans and the environment.

Have a question about an invasive species? Visit

What you can do:

  • Visit or download the app on your smartphone to report sightings of invasive species. Also report sightings of species to
  • Visit to learn how to ID invasives, see common look-alikes, and learn about management options.
  • Fight invasives! Armed with information, take an hour or a day to manage invasive species on your property, or volunteer with a local land trust or conservation organization to help control invasive species.
  • Become a Vermont Invasive Patroller with the Department of Environmental Conservation to help manage aquatic invasive species. (
  • Add invasive plants to your menu. Many invasives, including garlic mustard (Alliaria petiolata), goutweed (Aegopodium podagraria), and Japanese knotweed (Polygonum cuspidatum), are edible. Never eat anything unless you can positively identify that it is safe with 100% certainty.


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